3.4L white smoke on start up.

[subitoy]

My 3.4L start having some white smoke at cold start up. Recently my engine start to really shake and running rough at start up to the point that it can't idle by itself and needs higher rpm to run for the first 30 seconds. I have minimal coolant loss and white smoke lingers for a while so it's not just a steam. I did block test several times and there is no exhaust coming to cooling system. Seems like the leak at the intake. Not common for 3.4L and I could not find any threads on replacing intake manifold gaskets. Was wondering if anyone has any idea on what other tests to do and how to proceed.
Thank you for your help!

[jetwhine]

subitoy,

Have you tried a cooling system pressure leak down test yet? I would do that to see if you can see any fluid leaking anywhere. If not then you might have a minor head leak either from a head gasket or a crack in the head, though not as common. You can also look at the plugs and see which one is the cleanest and that would be the suspect cylinder.

[hevster1]

Originally Posted by subitoy

My 3.4L start having some white smoke at cold start up. Recently my engine start to really shake and running rough at start up to the point that it can't idle by itself and needs higher rpm to run for the first 30 seconds. I have minimal coolant loss and white smoke lingers for a while so it's not just a steam. I did block test several times and there is no exhaust coming to cooling system. Seems like the leak at the intake. Not common for 3.4L and I could not find any threads on replacing intake manifold gaskets. Was wondering if anyone has any idea on what other tests to do and how to proceed.
Thank you for your help!

Year, Mileage, Codes?
Intake gaskets are pretty easy. The plenum is 2 piece and easily removed to get to the main. Since you say you have minimal coolant loss I am guessing you do have some. If you have an early model, were the gaskets ever replaced? Have you ever overheated the truck? Does the exhaust smell like coolant? Have you tried a combustion gas tester/block tester to determine if there is this kind of problem?

[subitoy]

it's a 1997, 150k, no codes, I'm not original owner and don't know if HG were replaced. Exhaust does smells like coolant on start up.

Thank you for all replies. I was dreading that it might me more then just HG and I had some spare time today and did compression test. The engine was cool, did not want to burn myself.

Here are the results:








Cylinder 3 and 4 are not doing so good. If that would of been due to coolant leak it should of been clean, but those spark plugs look dirty.
Those spark plugs have only few hundred miles on them. I've been using synthetic oil with 5-6k between changes, engine does not burn oil, gives me 21mpg on freeway, 17mpg in a city.

What do you think the problem is?

[jetwhine]

subitoy,

The plugs are inconclusive. Another thing you can try is get the engine hot, then let it sit overnight and pull ther plugs out and look into each spark plug hole and see if you can see red or green anti freeze on top of the pistons. I say red or green depending on which type you use. Toyota's is red.
By the looks of the plugs #1 and #2 and #6 look the cleanest. #4 is probably oil because of the lower compresion.

[sam333]

Well you know you are burning coolant, just not from where. You can't let it go cause it will trash your o2 sensors and cat. I would pull the plugs and pressurize the coolant system(pump that fits on the radiator filler) then turn the engine over by hand and look into each plug holes with a flashlight. whether its a blown head gasket, intake or crack you should see coolant. You already know you have to do some disassembly of the engine to fix the problem. #4 is suspect because of the low comp. , even though its not washed clean. I have seen cracks in heads and cylinders that only open when cold( let coolant in )and then close up at operating temps. The low comp could also have nothing to do with a blown head gasket , but leaky valves or rings , but that cylinder is a problem either way.