Hello! I'm Noel, and I have compression issues.

Hey everyone! I can't tell you how helpful it's been to discover this forum. Now I know I'm not the only one who is pleased to see three Previas on the road in a single day. :thmbup:

I've been the proud owner of a 1993 LE 2WD for three years now. Aside from a new SADS a few years ago, its been a great work van. I am constantly amazed at what I can fit in it, and proud when I see other trucks and vans that cost far more, carry far less. I replaced the SADS, and consider myself handy, but inexperienced. I'm a carpenter and houses are far less complicated than cars.

I've had some time on my hands so I figured I'd give the blue beast the attention it deserved. I have a long laundry list of to-dos and at the top of that is making sure the drivetrain is going to get me to 300k. I'm at 278*** now and barring a heart attack, i think it will make it.

In Park it idles a bit rough and I can't tell if it is because my rebuilt SADS is bent/unbalanced, or if it's the engine. I tried the pipe clamp trick and it helped a little, but not enough. In gear this shimmy goes away and runs smooth (aside from a whistle at idle and a high pitched whirr under load). Again, my main goal is to get the engine tuned and head off any disasters.

I did a compression check today and I came up with 180/155/170/80. After adding some oil to 1 and 3, it measured 180/160/170/135. The numbers are scattered and they don't look good. It just got new plugs, cap and rotor, and will get wires tomorrow. However, after looking at the compression, it seems I have much bigger problems.

I'm curious to hear if its as bad as I think (or not) and if anyone might have some suggestions as a next step. It also sounds like there is gravel in the starter, it needs a new steering rack, and the A/C spins but doesn't get cold. Short of an engine rebuild, is this a project, or a parts vehicle for my next Previa?
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Hi Noel,

If you feel the van is worth it, make it a project vehicle. While it is still running rough, depending on time/money/space/knowledge you can fix the Previa up.

When I was looking for a Previa, everyone I came across has some issues, but one thing was common, they were all high mileage. I do expect it from these vans as they are 15+yrs old and have daily functional use (compared to a show car).

If anything, I would start with the compression/motor. That way your Previa is running and can be used.

-gravel in the starter, there is a thread where you can actually get some contacts points and plunger and the starter could be like new. Assuming your flex plate is not chewed up.

- Steering rack, I would replace

-A/C, if your priorities are to keep the van from dying, then I would just focus on the motor and parts to keep it running.

I can't say much about rough idle, maybe some kind of intake leak?

But let me add on to your laundry list (sorry about that). I feel these are issues that the Previas need addressing.

1st - EGR clean out - http://www.toyotavantech.com/forum/s...aning-write-up
2nd - IAC valve clean out and carbon flake filter. http://www.toyotavantech.com/forum/s...6568#post16568

Thanks cvtrodger, I've moved those items to the top 5 hits. Up until yesterday I was all ready to rehab as many components as I could get parts for. However, after the compression test I'm hesitant to really go all out if, at the end of the day, the gaskets or rings( or both) need to be replaced. That work is beyond my time, space and skill. I get the feeling this is a situation where I buy some additive and hope for the best. Does anyone have experience with products such as Bi-tron, Blue Devil, Restore, and those pellets you crush up and add?

The flake filter seems easy enough and cheap. How often do you change yours?

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Originally Posted by Noel

Thanks cvtrodger, I've moved those items to the top 5 hits. Up until yesterday I was all ready to rehab as many components as I could get parts for. However, after the compression test I'm hesitant to really go all out if, at the end of the day, the gaskets or rings( or both) need to be replaced. That work is beyond my time, space and skill. I get the feeling this is a situation where I buy some additive and hope for the best. Does anyone have experience with products such as Bi-tron, Blue Devil, Restore, and those pellets you crush up and add?

The flake filter seems easy enough and cheap. How often do you change yours?

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You can only do what you can. I never had experience with those products and personally, I would spring for engine repair or swap.

I have had my previa less than a year. I bought it with a blown head gasket in July of 2014. I had the motor rebuilt and recently transmission rebuilt. But I have been driving it since Sept of 2014 after the motor was done. I added the flake filter in October of 2014.

I've got to change out a couple other things and I will assess the flake filter to see if there is some carbon build up. But I was going to wait til October to change it out.

I've come up with the idea of doing annual maint of a few items. This includes the supercharger and flake filter.

Correct me if I'm wrong, but the double-wall plumbing deal that the "flake filter" is to address is used only on the S/C models.

Noel, from your compression numbers, rough idle and mileage, I suspect that your engine may be on its last legs. But this is typical of an engine with over a quarter-million miles. If you are content with the condition of the rest of the van and would like to drive it for another many years, I'd recommend planning for a JDM engine swap. An alternative would be to scour you local Craigslist for another one in better condition, reserving your current one as an organ donor. Got room? My strategy for driving older cars always involves a parts car.

Unless you're slowly losing coolant, you can probably nurse it along for a while. If it's losing compression due to ring wear, then the cylinder walls are likely worn as well, and repairing the engine becomes impractical compared to a JDM replacement. At any rate, watch the coolant and temperature levels closely because if it loses enough coolant to overheat and is run too long that way, the head will warp beyond repair.

I've seen engines with ruined heads and good blocks, and I have one now with a bad block and a good head. So they can go either way.

So far as I'm aware there is no easy/practical/legal way to fix an A/C system in a pre-'94 Previa if it needs a recharge. R12 was replaced by R134a with the '94 models. Even though I live in the NW where A/C is rarely needed for comfort around town, I like it on the highway so that I can close the windows to keep the noise down.

Not sure what the starter noise would be caused by, but it's not the electrical contacts. Could be the pinion is chewed up, or it could be that the last person who put in a starter didn't get all the bolts in or tight. Anyway, you can assess that when you drop the engine!

For what it's worth, I have a friend with a 95 Corolla. I replaced the timing belt and checked it over for him about 8 years ago. He was complaining about oil control issues and I found it worse compression readings than yours. At that time the car had around 225k miles on it so I recommended swapping engines or overhauling the one he had. He didn't want to spend the money and decided to drive the car until it dropped dead. To make a long story short, 8 years later he's still driving that car. It still drinks oil and idles a bit rough, and he's about to turn over 350k miles........wtf :dizzy:. I consider his a rare case, but just saying it's possible to still get lots of miles on something that's already worn out. I saw him the other day and asked if he wanted another timing belt put on it (he's way over due). He said no as he's still trying to kill the car. He claims it still gets good mileage and doesn't display any engine codes. He drives around with a gallon container of oil in the back seat & adds a quart about every 150 miles or so. Tim

PS: He also carries a gallon container of antifreeze and tops off the radiator at the same intervals as the engine oil :)>:

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Originally Posted by pdgizwiz

Correct me if I'm wrong, but the double-wall plumbing deal that the "flake filter" is to address is used only on the S/C models.

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You are correct sir. The S/C's only need to worry about it. I would suggest the IAC valve clean out if anything.

Thank you all for the advice. I think at this point I'm going to clean out a few valves to guestimate the gunk factor. I do know that the crankcase looked crusty when I replaced the PCV. I'll try to get photos when I do.

I was debating using a fuel/oil flush, oil change, then an oil additive to 'increase' compression.

However, the fear is that I may remove all the gunk that is actually keeping the engine alive, primarily any possible plugs in the headgasket. Worse yet, it might clog up the remaining open arteries with dislodged sludge.

I'm curious if anyone who has replaced a headgasket could attest to the leak plugging properties of engine gunk?

I guess I'm having trouble admitting that the best course of action is to do as little as possible. :no:

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Originally Posted by Noel

Thank you all for the advice. I think at this point I'm going to clean out a few valves to guestimate the gunk factor. I do know that the crankcase looked crusty when I replaced the PCV. I'll try to get photos when I do.

I was debating using a fuel/oil flush, oil change, then an oil additive to 'increase' compression.

However, the fear is that I may remove all the gunk that is actually keeping the engine alive, primarily any possible plugs in the headgasket. Worse yet, it might clog up the remaining open arteries with dislodged sludge.

I'm curious if anyone who has replaced a headgasket could attest to the leak plugging properties of engine gunk?

I guess I'm having trouble admitting that the best course of action is to do as little as possible. :no:

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hmmm. my buddy said the same thing, but I always try to address issues when it comes to gunk build up. I'm thinking if it is plugging a leak, it is also plugging other important passages. But I never let any of my cars get that bad. In fact, those are the first things I do when I get a used car.

Regarding engine oil flush products, here's a quote from another thread:

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As for your question regarding flushing out the lower end, I would advise against that. Nobody likes the idea of heavy sludge or chunks of scale floating around down there, but unless you tear down the bottom end, other than changing your oil there's not much you can do. Using crank-case flushing products on old engines is a bad idea. Scale or build-up doesn't do any harm when it's stuck to an engine surface. If the cleaning product actually works it will only serve to move the gunk from it's harmless position into a potentially bad one. When this stuff floats around in the pan it will typically end up stuck to the oil pump pick-up screen and if enough of it gets deposited there it can starve your engine for oil.

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"Using crank-case flushing products on old engines is a bad idea. Scale or build-up doesn't do any harm when it's stuck to an engine surface. If the cleaning product actually works it will only serve to move the gunk from it's harmless position into a potentially bad one."

Loud and clear. Thanks.

Regarding the A/C, I called around today and only a few shops have a machine with R12. Diagnosis includes an evac, pressure test for leaks, and recharge. It runs about $200 incuding 1lb of R12.

The kicker is the R12. Shops charge about $70 per pound. You can buy it for much cheaper on ebay/craigslist, but the shop can't use the cans. They can, but according to them, the cans would need to be put into the system (after the initial evac) then removed again so as to know how much was actually put in. Then it all goes back in to the proper amount. The extra labor may cancel out the savings of purchasing R12 yourself.

I think I may get some anyway just for topping up, knowing I run run the risk of overcharging. I still have bubbles in the sight glass, but it looks as if its a roiling boil. The A/C worked last year, so hopefully it's just a small leak that needs some leak stop and a top off. According to one shop, these systems are always leaky, even new off the line. The leaks are just so small that it takes a while to lose enough to matter.

Too bad Previas don't use a more modern coolant, Firestone has a $9.99 leak test coupon this month. I'm sure there's a catch, but every other shop I called charged ten times that for a diagnosis. That would be too easy. Where's the fun in that?

so convert to R134a... I took the plunge and didn't look back
it cools just fine so long as your engine doesn't have idling problems

read the AC002-98 TSB Toyota published... those are the official instructions on conversion

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Originally Posted by timsrv

Regarding engine oil flush products, here's a quote from another thread:

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Well, there you have it. Make sense if you are not going to tear down the block.

Well my van seems to have a weak cylinder, which is causing the idle to be be a bit rough. This is my reason for sticking with r12. I don't want to cause something else to crap out because of the added strain on the compressor and engine.

When you switched to r134, did you have the the expansion valve/orifice tube, condenser and O-rings replaced too? How much did the whole conversion cost?

The TSB says no flush is needed, yet I've read many times that it is crucial to get ALL the old stuff out.

I also read that any compressor that has Viton seals is not compatible with r134a. I take it the OEM compressor has Viton seals thus the need for new O-rings.

All this of course hinges on the leak test.

no flush was done
no o'rings changed
receiver drier changed and service port adapters added only

I put in the amount of oil and refrigerant Toyota specified and everything has been working great since

flushing is completely unnecessary as found in recent years as the old mineral oil will settle at the low parts of the system, while the PAG oil will get circulated

pressures were well nominal and only slightly higher than R12... no additional strain to compressor was noticed

As far as additives go, if everything is good, I wouldn't kick that dog.

However, when an engine gets to the point of having issues (low compression, oil burning, exc pinging.....) and the correct fix is to pull and rebuild.
There is some merit to trying "fix-it" products, to some degree.

In the case of an engine flush, using an effective and proven product, may buy you some more time.

I have seen engines that were flagged for rebuild, soldier on for another 100K.
I have also had engines where no success occurred and some that even got worse.
But seeing as the alternative is a full rebuild, it can be worth $15 of chemical and an oil change
My 2c

BB

Sorry Noel,

I should explain. I personally love my previa and I heavily rely on it for my family. With that said, It is why I push for rebuilding and fixing it.

Personally, I hate seeing good vehicles get thrashed. I know it is not my place to say what one does to their vehicle, but I've seen too many go to waste.

So I always give this sentimental value attachment along with car enthusiasts perspective.

What ever you choose, I hope it works for you.

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Originally Posted by Burntboot

In the case of an engine flush, using an effective and proven product, may buy you some more time.

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I understand about products like "Restore", Bars Leak, and similar gap filling products working, but are you advocating the use of products designed to flush and dissolve/remove sludge build-ups from an engine? I've torn down many old engines with heavy sludge build-up. Although messy to work on, I never considered sludge to be a serious problem (unless of course it broke loose and clogged something). In my experience sludge typically doesn't do that..........unless something designed to dissolve it has been added. I'd be interested in more information regarding your experiences with crankcase flushing products. Tim

If you're just thinking of trying to break loose stuck piston rings, what are your thoughts on simply putting a couple teaspoons of Seafoam or a similar product in each cylinder via the spark plug holes............then letting it sit overnight?

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Originally Posted by timsrv

If you're just thinking of trying to break loose stuck piston rings, what are your thoughts on simply putting a couple teaspoons of Seafoam or a similar product in each cylinder via the spark plug holes............then letting it sit overnight?

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Based on everything here, I think the flush is out. I added a can of Seafoam to the gas, but I'm going to skip any engine oil flush products.

The stuck ring theory is compelling, but if I add Seafoam will it wick all the way around the ring or just work on the low side since the engine is almost horizontal?

I do have a can of Restore as well but it would go in after any unsticking products.

Who knows. You're getting into the "witch doctor" area of mechanics with these products. I'm more inclined to tear things down and make them right (the old fashion way), but I realize not everybody has that ability. Let us know what you do and how it works out. Tim

if you want to clean anything out, go find and order AutoRX... it is the best "engine flush" there is as it is gentle and takes LOTS OF TIME to clear out whatever is in there. Since it is slow action, it will not quickly remove globs of sludge that will stuff up an engine. This stuff is often discussed on the BITOG forum and many will vouch for its safe effectiveness

You must use cheap regular oil though. No synthetics, no semi-synthetics, and no fancy extras in some dino oils. Otherwise it will not be effective

I've stumbled across a few heated discussions regarding AutoRX and it's effectiveness versus other products, in particular Kreen. People are very passionate about the stuff... I just had the oil changed recently so I'll let it ride for a bit and then consider a very gentle cleaner. I appreciate everyone's advice here. I'll keep this thread updated as I try different things.