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 :tapemouth 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

Edited July 3, 201113 yr by grantf

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

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

Edited July 3, 201113 yr by grantf

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

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

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!

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.