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/combus...tor-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.