Toyota Previa 1993 Smokey Exhaust

[gjr5088]

Hi there

I've been reading your great posts on this forum, especially about head gasket failures and how to repair
My 150,000 mile 1994 2.4L van smokes badly on start up , but once the water temp gauge levels, the smoking disappears
It is consuming coolant. I drive the van twice a week, for 1/2 mile to keep everything running ok - is this advisable??

Could I ask if you would be willing to watch a very short video to advise me what I should do next? [I can't seem to upload a video :-( ]
I live in United Kingdom near Liverpool. Unfortunately Previa specialists are very thin on the ground :-/

Very much appreciated
Kind regards
Gary Rimmer

[John Kaufmann]

It certainly looks like a head gasket leak on one of the cylinders, and the coolant loss seems to confirm it. Do you also see evidence of water in the oil?

I don't think it's a good idea to run it once a week until the head gasket is replaced, especially if there is water in the oil.

[gjr5088]

Hi there
Thank you very much indeed to take the time to read and reply to my message - much appreciated
I've not been able to investigate the water in the oil so far, but I will take a look.
Could I ask if it is normal that the engine, once warmed up, stops blowing smoke and appears to run normally once the engine is at normal operating temp? Initially my local Toyota garage suspected failure of the valve stem seals.
All the best
Gary

[John Kaufmann]

... I've not been able to investigate the water in the oil so far, but I will take a look. ...
Water will make the oil more of a milky (even foamy) light brown. That said, you can have a head gasket leak without getting water in the oil.


... Could I ask if it is normal that the engine, once warmed up, stops blowing smoke and appears to run normally once the engine is at normal operating temp? Initially my local Toyota garage suspected failure of the valve stem seals. ...
Worn valve stem seals let oil leak into the cylinders when the engine is not in use, resulting in a puff of blue smoke when you start up. That small amount of oil usually clears pretty quickly, regardless of temperature -- and after that burn-off, the small amount of oil that may leak is not enough to cause visible smoke. [I had to replace mine once.] It is a nuisance, to be fixed as soon as practical, but does not threaten the engine.

The head gasket leak is more temperature-dependent, as the warming aluminum head squeezes down on the block, so the cloud typically is whiter and lasts longer -- though a bad head leak can continue even at high temperature.

[Previologist]

Could I ask if it is normal that the engine, once warmed up, stops blowing smoke and appears to run normally once the engine is at normal operating temp?

Yes. it is normal for a leaky head gasket to behave that way.

No you shouldn't drive it, because you risk more serious damage. Not sure if there is an equivalent in the UK but in the US you can get a pretty cheap kit that will detect exhaust gas in your coolant and confirm the leak. https://www.harborfreight.com/combustion-leak-detector-64814.html

But based on your pictures I would say you definitely have a head gasket leak. While coolant in the oil will also confirm it, in my experience with a couple of Previa head gasket leaks I got oil in the coolant but not the reverse. In the early stages you might not see either one.

[timsrv]

Another clue would be the smell of the exhaust. If it's coolant it will smell like antifreeze.......and yes, like the others have said, smoking while cold then clearing up after warm-up is fairly typical of a blown head gasket on these.

There are "stop leak" products out there that can fix, but I'm not crazy about these as they can create other problems. If you plan on fixing it right, then don't use a stop leak product. If you're not going to fix it and just want some more miles, then they can be useful. I have love/hate feelings about these products. The love comes when it saves your bacon by allowing you to put off fixing the right way. The hate part is when you do finally fix it and the coolant system is contaminated (that can cause radiator problems, water pump issues and/or cause the T-stat to stick). A couple of years after I sold my Previa to a friend (about 10 years ago) it blew the head gasket @ ~ 200k miles. He put "Bars Leak" (https://www.amazon.com/Bars-HG-1-Blown-Gasket-Repair/dp/B003RGIWO0/ref=asc_df_B003RGIWO0/?tag=hyprod-20&linkCode=df0&hvadid=693070740373&hvpos=&hvnetw=g&hvrand=876377297841385292&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033612&hvtargid=pla-405660693568&psc=1&mcid=fadf3aa229ea3a708a2fb898cf9fae86&gad_source=1) in it and that stopped the leak. He has considered that van to be on it's last legs for the last 8 years but the gasket is still holding and he's put ~80k miles on it since then (so far no other ill effects have presented themselves). Your mileage may vary. Tim

[gjr5088]

Hi Tim
Thanks very much for taking the time to reply
I have the Previa booked in for assessment at a local garage at the end of July, recommended by my Toyota garage. The owner/technician comes hight recommended, so I would like to direct him to this website, should he need to benefit from the detailed threads that many users (and yourself) have generously posted. Thanks for suggesting the leak-fix products, but I'd prefer to go down the full repair route! I'm just hoping that the necessary parts are somewhat easy to source [fingers crossed]

I'll keep the group updated, and extend my thanks for the support received so far :-)

All the best
Gary

[gjr5088]

Hi Everyone

By way of an update. I am a couple of weeks away from getting my Previa transported to the garage who has agreed to attempt the head gasket repair.

My local Toyota main dealer has ordered a replacement head gasket. It was showing in stock at Toyota (Japan, I suppose), so fingers crossed it should arrive in a few weeks.

Unfortunately, the head gasket repair kit is showing as obsolete and unavailable to order.

Does anyone have any experience of an online source for repair kit T04112-76071 please?

Many thanks to this important group!!

All the best
Gary

[John Kaufmann]

. . . Does anyone have any experience of an online source for repair kit T04112-76071 please? . . .
I presume you know of ToyotaPartsDeal (https://www.toyotapartsdeal.com/oem/toyota~gasket~kit~engine~v~04112-76071.html?vin=&make=Toyota&model=Previa&year=1994&submodel=&extra1=&extra2=&filter=(d=USA;1=2TZFE;4=LE;5=ATM;7=07S;9=EFI;0=TCR 10L-RFSGKA))?

[Previologist]

I've been trying to figure out what exactly is in a 'valve grind kit" but haven't had any luck. Is it really necessary for a head gasket job?

[gjr5088]

Hi there

By way of an update.

My chosen repair garage finished the head gasket and seal repair job using Victor Reinz 02-52850-01 kit

He noticed some scoring inside the cylinder head bores, so he elected to machine the bores and install larger diameter pistons

So all in all a bigger job than initially planned

Got the van back and it ran beautifully for about 10 days

Then noticed the return of the smoking

Long story short, back to square one

So I now have it booked in 3rd week in Jan with another gasket repair kit in hand.

Question:
I have been running it for approx 100 miles since rebuild and currently on most days the smoke stops once the water temp gauge reaches normal
what else might be causing the return to the state of a coolant leak??

Any ideas would be very gratefully received

All the best
Gary

[Previologist]

Ugh, that's awful. :no: My suggestion is use OEM gaskets. There are several 1111576040 available in UAE, if you can't get access them through ebay try megazip. I presume those will work on your Previa but being European you'll need to verify it


And don't drive it. It is normal for Previas to stop "smoking" after they warm up with blown head gaskets. You can do a test for exhaust gases in coolant to verify the diagnosis.

Hopefully the shop with do it for free?

[gjr5088]

thanks for the tip about Megazip!
I'll keep the group updated :-)

[timsrv]

I'm very sorry to hear that. There are several ways coolant can get into combustion areas but in my experience the only one that "clears up" when warm is the head gasket. Cracks and/or defects in the cylinder head or block can also allow coolant to enter the cylinders, but these don't clear-up or go away as the vehicle warms. Head gasket leaks can clear-up because the composite material they are constructed from gets softer and seals better when warm.

If the gasket is to have a chance of sealing it needs flat surfaces. An important step in the replacement is to check the block deck and the head for flatness using a straight edge and feeler gauges. Equally important is to check these surfaces (especially the head) for erosion in the areas between the water passages and the combustion areas. If the block and/or head have defects in the gasket contact areas, it could lead to early gasket failure and/or prevent the gasket from sealing. If there are such defects, these can usually be remedied with some light machine work to the surface areas (known as decking). Care in assembly is also important. Foreign material, dirt and/or grease, or any other contaminants on the surface areas need to be thoroughly cleaned before assembly. If said care is not taken, seal integrity can be compromised. Torque values and tightening sequences are also important.

These engines in particular are prone to head gasket issues. I know Toyota initially had some issues with head gasket failures within the 1st 2 or 3 years of production so they redesigned/improved the head gaskets. After the new/improved gaskets went into production the gasket issues faded. It sucks that Toyota does not provide gaskets anymore as I think their 2nd versions were the best ones. It's possible some aftermarket brands might also be as good, but I have no idea which ones those may be. If everything else checks out and it does turn out to be a bad gasket, I'd recommend trying a different "premium" brand this time. Tim

[timsrv]

Ugh, that's awful. :no: My suggestion is use OEM gaskets.........

If you can find an OEM gasket, I agree, this would be your best course of action.

[gjr5088]

Hi Tim

Fabulous reasoned response
I will convey to the guy who will be affecting the repair

All the very best
Gary

[timsrv]

No problem, I'm just sorry you need to deal with this again :doh:. In case you don't already know about it there is some more useful information on THIS THREAD (https://www.toyotavantech.com/forum/showthread.php?552-Replacing-a-Previa-head-gasket)

[gjr5088]

* Bookmarked *

thank you :-)

[Previologist]

If you can find an OEM gasket, I agree, this would be your best course of action.

OK, good, I was about to ask you to clarify your comment about premium aftermarket gaskets. The newer OEM head gasket is, I believe, the number I gave above and it is most definitely still available.

[gjr5088]

Hi Everyone

The engine has bee removed for a second time. A cracked cylinder head block has been identified - nightmare scenario!

I can imagine that a replacement cylinder head is not easy to find. Can I ask the group if you know of any blocks that might be considered, or any other routes to rectify the problem?

Big ask I know, but this is the best resource on the net for help, so thank you :-)

All the best
Gary

[Jonny]

Here is a recent thread with some cylinder head info.

https://www.toyotavantech.com/forum/showthread.php?8822-Replacing-head-1992-2TZ-FE-The-Saga-of-Njordi

I am in the same position with a cracked head and have done nothing except call CHI - they do have 2TZ-FE heads as of a couple of weeks ago.

Just to be sure we're on the same page... as I understand it, the part of the engine with the camshafts and valves (above the head gasket) is commonly referred to as the cylinder head, the part with the cylinder bores and the lower stuff (below the head gasket) is the engine block. Referring to a cylinder head block might be confusing to some (like me!) or might cause assumptions to be made (always bad!). If you were referring to the engine block, my apologies for an irrelevant link, above.

[Boerderij_Kabouter]

I have my head from CHI back on the van. I need to finish buttoning everything up, but I am pleased with CHI. I am pulling together a full technical bulletin for replacing the head gasket using Samay's method (Previa Legend) without removing the engine. It has helped me keep the project straight, and will hopefully help folks in the future tackle this project with a lot more confidence and less time watching the youtube videos a million times. I am including torque specs and pictures where I thought appropriate. I should have it posted after this weekend.

All cleaned up and back together!
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