The Cooling System Troubleshooting thread

Happy Day of Thanks to all of you happy TV owners!!!

So, I would like to be the first in this thread. After searching all around here and TVP, I have yet to find my problem listed. It was mentioned in this thread http://www.toyotavanpeople.com/forum...p=58889#p58889, which I just posted my scenario on.

Here's what happened. Yesterday driving down I-5, doing 65-70, just before The Grapevine, noticed that my temp had risen to about 3/4. Usually it slightly points down from center. I replaced hoses (Napa), WP (OEM), Rad Cap (Napa), and rebuilt fan clutch, about 500 miles ago since WP blew and clutch was poor,,, and OEM t-stat about 4k miles ago. Never had any overheating issues, except when WP failed. So,,, saw the van getting hot, pulled over at a station to let it cool. Checked overflow, and it was perfect. Once engine cooled enough I pulled rad cap and started engine and level was normal. Started up grapevine since temp was low. Driving 45, 1/2 way up noticed temp building again,,, so pulled into rest stop and everything was the same. No noticeable issues?!?!? Temp climbed again as I completed the rest of the climb, then dropped to normal coming down the backside. My pops lives in Venice and the temp was absolutely normal for the rest of the 2+ hour drive. Any thoughts or suggestions? It's hard to believe that a brand new Napa rad cap could be the culprit, but I'm willing to get an OEM cap if folks think that could be it.

As usual, it sounds like there may be more than one problem.

First, an overflow tank that does not go down combined with coolant missing at the filler neck indicates a problem with the system between the rad cap and the coolant tank.

I'm not a believer in OEM radiator caps, at least not at this point in time; my vans are (one by one) getting Stant or NAPA and I haven't yet found a new cap that was bad (or went bad at an early age). However, others have reported this, so it would be worth replacing just to see if that gets the coolant communicating properly with the overflow tank.

The other common culprit, IME, is the hose from the filler neck to the overflow tank. I've had to replace that on a lot of vans lately. You can use bulk 5/16" hose or order OEM (which is what I do), Toyota P/N 85338-73010.


Next issue is finding the source of the actual running-too-warm problem.

From your description, I'm suspicious that it is not related to coolant loss, specifically because (1) you said you only "topped off" the coolant at the filler neck (rather than exclaiming "wow, it took a whole bunch") and (2) the van only got hot when stressed, but continued on just fine for the last part of the drive, a significant length of time, which it would not be able to do if coolant was steadily leaving the system.

With the combined symptoms of no significant coolant loss, working fan clutch and t-stat, and getting abnormally hot under stress (but not with regular driving conditions), I strongly suspect the radiator is starting to get clogged up and needs to be recored SOON. Preferably before going over any more hills.

If you have to get home and are not running with the heater on, DO turn it on if the temp starts to go up and that should help. If you are already using the heater cores, plan to give the van plenty of "rest stops" on the way, and stay alert for the cabin heat suddenly going cold (pull over IMMEDIATELY if that happens), which would indicate massive coolant loss. Then get that recore done ASAP after you get back.

Gwen

Yes, and also check for debris on the front of your radiator. Sometimes you can get quite an accumulation built up there over time.

If you do get a re-core, I strongly recommend going with a custom built unit with an extra row of cooling tubes. NEC has a source in Yuba City, CA that's doing this for a very reasonable cost.

BTW, what's the story on that rebuilt clutch fan.....is it an aftermarket brand or did it come from Toyota? Tim

PS: I've been running Gates #31333 radiator caps for years and have been happy with the performance. You can get them at www.rockauto.com for about $5. Tim

Thank you Gwen & Tim for your replies. NEC replied to my thread on TVP. He and I have talked about stuff before and has mentioned the Yuba city radiator source for the recore. I just got a radiator from Wondervan's recent '89 4wd parts van. When I get back north, I will have both tested and if either/both are bad I'm getting the recore, but if one is good I get to save some money for now. I slightly modified my original post, as I meant it to read that H2O levels were all fine, no H2O loss was observed. When I pull the rad, I'll also check for blockage on the rad or in front of it. Once again, thank you for imparting your thoughts, it makes being a new TVP owner so much more enjoyable and stress free. Hope y'all's holidaze were enjoyable.:drunk:

Hey VanSurfer,

Any updates? Did you have the re-core done by Ability Radiator in Yuba City?

I'm planning on doing that in about a month. I'm also thinking about gutting the entire a/c system to free-up some airflow space in front of the radiator. Anyone else get rid of their a/c system and have good results?

Thanks,

-Mark H
San Diego, CA.

I've completely removed the A/C on several vans now. Judging from the dash temp gauge alone (which is anything but sensitive, and also varies from van to van), they definitely run cooler. Maybe TOO cooler in the winter (as the operating temp falls below optimum, fuel economy also falls).

Gwen

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Maybe TOO cooler in the winter (as the operating temp falls below optimum, fuel economy also falls).

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Interesting. Do you think the 4 row high efficiency rad might be overkill?

IMO there is no such thing as "too cool" The thermostat opens up at 185 deg F.........the rest of the time it stays shut (unless it's stuck open). Of course the heater hose circuit bypasses the thermostat, so I guess it's possible to "over cool" the engine if it's super cold out and both heaters are on high. I have never experienced that problem, but I wouldn't rule out the possibility. Tim

Quote:

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Originally Posted by timsrv

[...] the heater hose circuit bypasses the thermostat, so I guess it's possible to "over cool" the engine if it's super cold out and both heaters are on high.

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That's what I'm talking about — using the heater in the winter. I have to delay turning the heater on (the colder outside, the longer the delay) and once it's on, the operating temp doesn't climb any further. Same problem as with my 3Y van that never had A/C, except not quite as bad for the 4Y 4WD. I wouldn't call the results "over cool", just that it's sub-optimal operating temperature — a stuck-open t-stat is a WAY better example of "over cool." :dizzy:

YMMV, especially depending on your climate!

Gwen

I don't use my rear heater. On cold days the front heater goes right to high from the moment I leave the driveway. It takes about 5-10 miles (depending on how cold it is) for the temp to reach normal. You're at a higher elevation than me though (I'm less than 300' above sea level), so I'm sure you're dealing with colder extremes. Perhaps a block heater may be in order? Tim

llamavan wrote:

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The other common culprit, IME, is the hose from the filler neck to the overflow tank. I've had to replace that on a lot of vans lately. You can use bulk 5/16" hose or order OEM (which is what I do), Toyota P/N 85338-73010.

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Llamavan's comments about the radiator overflow hose got me thinkin'. I cut/pulled it off. The little metal overflow tube coming out of the filler neck is totally corroded. I pushed a nail thru the metal tube to clear it and make sure that it's free to flow. I had the new rubber hose on hand so I cleaned up the tube as best I could, put some grease on it, put the new hose on and hose clamped it. This is temporary until I get a new filler neck. The old overflow hose had a bunch of rusty corroded gunk in it and no doubt it was restricting the flow of coolant. Hopefully the fillernecks are still available.
Anyone know the part # for the filler neck?
Some pics below:

Update: I drove around yesterday for a couple hours running errands. Usually I leave the cabin heater on to help cool the engine. Yesterday I didn't do that to see what would happen. When I got home parked in my garage, I popped the engine lid and guess what? No coolant coming out of the overflow tube this time. I guess my temporary fix worked. I have the new radiator filler neck & gasket on order from 1st Toyota parts.

Thanks to llamavan for pointing out that little overflow hose as a likely culprit!:clap:

My electric cooling fans never let the temp gauge go over half way. But I still intend to have the new manual temp control relays installed to get it just right as per Tim's recommendations. I will update when that happens.

P.S. I'm still having to add coolant at the filler neck. Not much, maybe a half a cup for each 20 miles I drive it. I still suspect I have a minor head gasket leak.

Quote:

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Originally Posted by timsrv

IMO there is no such thing as "too cool" The thermostat opens up at 185 deg F.........the rest of the time it stays shut (unless it's stuck open). Of course the heater hose circuit bypasses the thermostat, so I guess it's possible to "over cool" the engine if it's super cold out and both heaters are on high. I have never experienced that problem, but I wouldn't rule out the possibility. Tim

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I have experienced this on a few vans,with factory rads and a/c. its a good thing that the engine seal was gone on one so i could enjoy some warmth, because it took forever to warm up

Hello! I recently replaced my thermostat because of a huge puddle of coolant under my 85 van. Probably about a year ago. The same situation just happened and seems like the same problem.
I too have a properly full overflow tank, and what look like very new hoses,, but the engine was almost to red when I pulled over.
I’m wondering what my next move is. I would like to not have to keep replacing the thermostat? I’m thinking I need a new radiator? (I’ve only had to do a couple of things to my van so far so pardon my lack of know how!:wave2:)

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Originally Posted by llamavan

As usual, it sounds like there may be more than one problem.

First, an overflow tank that does not go down combined with coolant missing at the filler neck indicates a problem with the system between the rad cap and the coolant tank.

I'm not a believer in OEM radiator caps, at least not at this point in time; my vans are (one by one) getting Stant or NAPA and I haven't yet found a new cap that was bad (or went bad at an early age). However, others have reported this, so it would be worth replacing just to see if that gets the coolant communicating properly with the overflow tank.

The other common culprit, IME, is the hose from the filler neck to the overflow tank. I've had to replace that on a lot of vans lately. You can use bulk 5/16" hose or order OEM (which is what I do), Toyota P/N 85338-73010.


Next issue is finding the source of the actual running-too-warm problem.

From your description, I'm suspicious that it is not related to coolant loss, specifically because (1) you said you only "topped off" the coolant at the filler neck (rather than exclaiming "wow, it took a whole bunch") and (2) the van only got hot when stressed, but continued on just fine for the last part of the drive, a significant length of time, which it would not be able to do if coolant was steadily leaving the system.

With the combined symptoms of no significant coolant loss, working fan clutch and t-stat, and getting abnormally hot under stress (but not with regular driving conditions), I strongly suspect the radiator is starting to get clogged up and needs to be recored SOON. Preferably before going over any more hills.

If you have to get home and are not running with the heater on, DO turn it on if the temp starts to go up and that should help. If you are already using the heater cores, plan to give the van plenty of "rest stops" on the way, and stay alert for the cabin heat suddenly going cold (pull over IMMEDIATELY if that happens), which would indicate massive coolant loss. Then get that recore done ASAP after you get back.

Gwen

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So here is what I have found, at least for me, to be an accurate list of cooling system overhaul. Total cost on my end was about $180.00 to go through the entire system and repair/ replace things as needed.

I went through the entire cooling system.

1. Hoses. Inspect them all. Any bulged, plugged or hard/ brittle ones got replaced. I prefer goodyear, gates or continental for these. Some will have to be made from a roll of bulk hose (various sizes).

2. Thermostat. New to you van? Just replace it with either a oem Toyota OR the Aisin one from Rock Auto is a great substitute. Don't forget the rubber gasket that fits around it. This item alone causes more headaches. 185* is what the open point is. They are cheap, just swap it.

3. Water Pump. Aisin is literally the best alternative here. Quality bearing and prop in these units. Paper gasket included (and yes, you will want a thin film of fipg). The pump gets weak over time, the bearing wears and pending on what the PO has run through it, or lacked in service... this parts cheap enough to just swap.

4. Fan Clutch. Aisin FCT 037. A 60 dollar part thats easy enough to test and replace. Lots of cooling issues get tracked to right here.

5. Filler neck cap. 13 lbs. Just swap it. Stant, Gates, OEM, Napa are good choices. I prefer the cap with the pressure release.

6. Heater cores. After 30 years, they get a lot of build up. Flushing may not get it clear! See Radiator comment below.

7. Radiator (and engine block/ head). This one gets overlooked ALOT and is usually inspected last for whatever reason... most likely cost related. Yank it and give it a vinegar bath! 2 days filled with white distilled vinegar and a good flush with the hose (can do the same with heater cores)! Outside of peeling the tanks and having it rodded or just a full blown replacement, this is the next best alternative! Vinegar is effective enough without being overly harsh to remove that caked on calcium and ore build up. You'd be shocked what gets flushed out with the ol' hose. And FLUSH it with the hose BOTH WAYS. The block should be flushed also. Pull the block drain plug and flush from the filler neck.

8. TUNE. These little 4y's are really susceptible to tuning! The timing and idle speed play a larger role than you would expect in how they cool. I made a 5 degree difference in temp just by adjusting to the proper timing. Adjust idle speed to normal range.

Note about the og temp gauge and sending unit.... it's 30+ years old. Trust it if you like, but validate it's accuracy at least. Mine read a bit high, only to find the sending unit was out of whack. Plus, lets face it... it's just an idiot light/ indicator. I wouldn't put lots of stock into it. Consider an upgrade to a digital read unit like so:

https://www.amazon.com/Koso-North-America-BA024R10-Temperature/dp/B07HF6XPX1/ref=sr_1_2?keywords=koso+temp+gauge&qid=1571241883 &s=automotive&sr=1-2-catcorr


Stay cool.

Great post @Flecker. thanks:clap:

Quote:

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Originally Posted by Flecker

So here is what I have found, at least for me, to be an accurate list of cooling system overhaul. Total cost on my end was about $180.00 to go through the entire system and repair/ replace things as needed.

I went through the entire cooling system.

1. Hoses. Inspect them all. Any bulged, plugged or hard/ brittle ones got replaced. I prefer goodyear, gates or continental for these. Some will have to be made from a roll of bulk hose (various sizes).

2. Thermostat. New to you van? Just replace it with either a oem Toyota OR the Aisin one from Rock Auto is a great substitute. Don't forget the rubber gasket that fits around it. This item alone causes more headaches. 185* is what the open point is. They are cheap, just swap it.

3. Water Pump. Aisin is literally the best alternative here. Quality bearing and prop in these units. Paper gasket included (and yes, you will want a thin film of fipg). The pump gets weak over time, the bearing wears and pending on what the PO has run through it, or lacked in service... this parts cheap enough to just swap.

4. Fan Clutch. Aisin FCT 037. A 60 dollar part thats easy enough to test and replace. Lots of cooling issues get tracked to right here.

5. Filler neck cap. 13 lbs. Just swap it. Stant, Gates, OEM, Napa are good choices. I prefer the cap with the pressure release.

6. Heater cores. After 30 years, they get a lot of build up. Flushing may not get it clear! See Radiator comment below.

7. Radiator (and engine block/ head). This one gets overlooked ALOT and is usually inspected last for whatever reason... most likely cost related. Yank it and give it a vinegar bath! 2 days filled with white distilled vinegar and a good flush with the hose (can do the same with heater cores)! Outside of peeling the tanks and having it rodded or just a full blown replacement, this is the next best alternative! Vinegar is effective enough without being overly harsh to remove that caked on calcium and ore build up. You'd be shocked what gets flushed out with the ol' hose. And FLUSH it with the hose BOTH WAYS. The block should be flushed also. Pull the block drain plug and flush from the filler neck.

8. TUNE. These little 4y's are really susceptible to tuning! The timing and idle speed play a larger role than you would expect in how they cool. I made a 5 degree difference in temp just by adjusting to the proper timing. Adjust idle speed to normal range.

Note about the og temp gauge and sending unit.... it's 30+ years old. Trust it if you like, but validate it's accuracy at least. Mine read a bit high, only to find the sending unit was out of whack. Plus, lets face it... it's just an idiot light/ indicator. I wouldn't put lots of stock into it. Consider an upgrade to a digital read unit like so:

https://www.amazon.com/Koso-North-America-BA024R10-Temperature/dp/B07HF6XPX1/ref=sr_1_2?keywords=koso+temp+gauge&qid=1571241883 &s=automotive&sr=1-2-catcorr


Stay cool.

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A little item of fairly high importance omitted, if I may:

9. Fan shroud: verify that the bottom part of the shroud is there. If not, or not sure go there https://www.toyotavantech.com/forum/...wer+fan+shroud

Quote:

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Originally Posted by Carbonized

A little item of fairly high importance omitted, if I may:

9. Fan shroud: verify that the bottom part of the shroud is there. If not, or not sure go there https://www.toyotavantech.com/forum/...wer+fan+shroud

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Doh! True story!!! I take mine for granted because my van came with it intact. It does play a big role in putting the air where it needs to be.

Good catch!:thmbup:

Hello Guys
I have a Toyota Spacia YR22 VAN, with a 4YEC engine pretty much the same configuration as the Toyota Van

So my problem is that I fill coolant up to the filler neck and coolant does not stay to the top of the filler neck.

I have done a air bleed with the coolant funnels, no bubbles or air is coming out just like a pulsation so I know the coolant level is good and bleeding unless this is a problem
https://www.youtube.com/shorts/N8ZfAjShabI

After I made sure the coolant was full at the filler neck I topped up the coolant reservoir just in the middle between low and full

I have filled the coolant reservoir to full before but, I have somewhat of a steep driveway so if I park forward on a decline and get home from work when the engine is warm and shut the car off, coolant starts dripping out from the reservoir overflow hose, this could be a reason as to why the filler neck is low after a top up.

But I have kept monitoring it and always my filler neck seems to be low even past the sensors.

This is what it is like at the moment.

Attachment 13391

Attachment 13392

Attachment 13393

I have also noticed coolant leaking at the overflow hose from filler neck to coolant reservoir as per last photo. Also my coolant temperature gauge hasn't been working so I dont know what the temperature is sitting at I bought the car like that, but it has had a new radiator, viscous fan, and water pump replacement and thermostat replacement, and brand new upper and lower radiator hoses as per the invoices and I dont know if its overheating or not but I think the previous owner has been driving it like that for a while, also the overflow sensor float is broken so its currently disconnected also sealant has been used on the bottom of the overflow reservoir I suspect they had a leaky rubber gromet at one stage and have done a dodgy patch up job. I have not really noticed any coolant leaks on my driveway mainly just from overflow hose.

So for now I am thinking doing these steps.

1. Replace Radiator Cap
2. Replace Filler Neck to Overflow Tank Hose
3. Aftermarket Overflow Tank for the time being and see if I can save the old sensor and get a new genuine overflow tank and gromet or dorman gromet as I have seen in other forum post.

I may also do some diagnostics saw someone place a cup where his overflow hose might use a plastic water bottle and see if coolant flows to the plastic water bottle if so would that indicate system not holding pressure.

Anyway I will see how I go just wondering if anyone could give some tips if they have experienced a low filler neck after bleeding.

I will try the steps illustrated in the green text and see how I go.

Kind Regards
KNIBBZY

The overflow system works under the principals of pressure and vacuum (suction). As the temperature increases the coolant expands. Expansion creates pressure and when pressure exceeds the rated pressure of the radiator cap, it allows coolant to vent out the filler neck and into the recovery tank. This function is relatively trouble free as transferring liquids by pressure is fairly reliable.

The weakness/trouble usually comes with returning it to the engine. When the engine cools the coolant retracts. The resulting vacuum basically sucks the coolant back from the recovery tank (much like sucking a beverage from a straw). If there is a breach in the straw/hose or anywhere between the recovery tank and the block, it will suck air from the breach instead of coolant from the tank. A breach anywhere in the cooling system........especially higher up (like a failing head gasket) can result in the same issue (as it is easier to suck air than liquid).

So I'd recommend starting out by replacing the hose between the recovery tank and the filler neck and the radiator cap. Also make sure the filler neck (the part where the rubber of the radiator cap contacts) is flat and free of pits and scratches. Hopefully the problem is external because a head gasket is not much fun on one of these. Good luck. Tim

PS: The water jacket side of the block/head is the same side as the intake/exhaust manifold. Inspect that side of your engine to see if there's any evidence of coolant seeping/dripping down from the head gasket.......usually near the back closer to the firewall. You should also check your "hoses of death" and the coolant hoses going to your throttle body to see if there's any evidence of leakage there.

:whs:

And yes, replace the radiator cap first. Simple, cheap, and quite possibly the culprit.

Gwen

Hey guys so an update on the cooling system for my 1994 Toyota Spacia 4YEC Engine, Replaced the coolant radiator cap and filler neck to overflow coolant hose and installed a aftermarket coolant gauge, been driving the car and my coolant does not get above 90 degrees Celsius / 194 Fahrenheit and when warm stays between 77 - 87 degrees Celsius / 170 - 188 Fahrenheit so I think its safe to say the cooling system is running fine and I have no overheating problems or issues and I dont see any green coolant on the floor or driveway and when warm the overflow is full and normal and when its cools downs retracts back. Also cool feature about the water temp/coolant gauge is I can set a static temperature to give me a warning if the car is starting to overheat and it will start beeping.

Here is a video of the coolant gauge after a road test:
https://www.youtube.com/shorts/jvz8wP6aHJU

So my cooling issues are still persistent, its winter here in Australia so we have been getting cold mornings and cold afternoons, the coolant gauge allows me to see what my temps are at, short trips it has been fine stays around 80 to 90 degrees celsius, but the other day I got stuck in a traffic jam 1 hour of stop starting driving, then turns out a semi truck was broken down between a 4 way traffic light intersection which blocked all directions I had to do a u-turn and drive onto the freeway to get home a 40 minute detour, when on the freeway I was travelling 100 km/h for 20 mins my temps kept creeping up to 95 to 100 degrees, then when I got off the freeway exit and was stopped at the traffic lights the temps kept creeping up to 105 - 107 degrees and went up and down until I got home. I am gonna do these things:

- Replace Thermostat
- Flush Cooling system see if any gunk is stuck in the radiator, possibly take radiator out depending how lazy I am
- Replace upper and lower radiators hoses
- Replace Coolant Sensors

I am also wondering how does the viscous fan work and what detects the fan to kick in, I dont really hear my fan kick it and suspect that maybe its not working, is it a sensor or is the oil in the viscous coupling that makes the fan kick in when it gets to hot.

Check out this thread: https://www.toyotavantech.com/forum/...upling)-Thread

After many confusing months and my cooling system giving me woes and problems, I have finally figured out why my cooling system was losing coolant every so often and my overflow would be near to empty.

It was good I replaced these components with new parts in time for summer here in Australia that is coming up this will give me reassurance that my van will survive summer, so I am not to bummed that I spent money on these things such as my:

- Radiator Cap
- Thermostat
- Water-pump
- Upper and Lower Radiator Hoses
- Overflow Hose from water outlet to overflow reservoir
- New Toyota Long Life Coolant (Toyota Red)

Now for the final reveal what was making my car lose coolant, THE WELCH PLUG/FREEZE PLUG ON THE LEFT SIDE OF THE ENGINE BLOCK, The second welch plug on the engine block had built up coolant around it and corrosion and there was a trail of coolant going down the block all the way back to my gearbox I had a look and yep when the car was warm and running, there was coolant weeping out of the welch plug, so I have finally figured it out after many months, for the time being I have just gooped some Toyota Black Sealant on the welch plug until my new ones come in from Toyota to be replaced, luckily its the second one so I can have somewhat easy access to the welch plug and can replace it with not to much struggle fingers crossed. So guys and girls check your Welch/Freeze plugs to if you have replaced everything on your cooling system and your car is still overheating or losing coolant.

All The Best
KNIBBZY
Attachment 13539