F@CK!!! I think I have a blown manifold gasket!!!

[grantf]

If you have been reading my timing and mpg thread you will get more info.
I think I found the culprit being the TPS. My car was running good today up until I decided to clean some crud from the engine using simple green. The engine was still hot when I sprayed lightly on all sides of the engine block then I rinsed it with water out of a squirt bottle being careful not to wet the electrical components. the car sat for about 2 hours and then after starting up it ran like crap. I hooked up the mighty vac to test for vacuum and got about 10 hg I was getting near 16 before. after revving the engine I saw what looked like exhaust coming from the rear end of the manifold gasket.
It looks like I need a new one. I have never replaced this gasket before and it looks like a TON of work to replace. Any advice please

[robftw]

manifold gasket on the block? or where the exhaust pipe connects to the manifold

[grantf]

The block.
So this would be the intake and exhaust gasket. I actually tightened the rear most nut. surprisingly I got about a 16th of a turn out of it. Normally I would expect the nut to not budge at all being a rusty exhaust bolt. My vacuum is back to near 15 in Hg. So I am thinking that my vacuum being low may be due to the an intake/exhaust manifold leak. I believe that nothing detrimental occurred from my engine cleaning and that this may not be a new symptom.
May I ask the forum administrator to revert this thread to my timing and mpg thread, My apologies

[71Nissan240Z]

when ever you shock aluminum, steel or any other metal with hot and cold flashes it tends to make the molecular structure change.

[bobc]

Be careful tightening those nuts, especially when they are hot. You can break a stud off in the manifold and then you've got a whole new set of problems to take care of!

Best,

Bob

[grantf]

Arrrg! this is my own fault for posting the above so quickly. No I do not think I "shocked" any metal, nor cracked or re tempered, or stressed anything. Also I have not forced any bolts hard enough to snap anything, my "snugging" down bolts was by hand only using a box end wrench, little force if any. I would prefer advice on increasing manifold vacuum and leaning out the mixture on efi systems. Really! what would happen if I was driving on a hot day for 3 hours and then hit a mud puddle? Really now! come on!

[cozye]

as I mentioned in the other thread, use carb spray or propane while running to identify an intake manifold leak. If you have one, you need to fix it asap. It's not a difficult job if you are patient with the rusty studs.