higher compression than oem

[spatulahunter1]

I had some oil in my coolant so i was worried that i might have a bad headgasket. I decided that it would be a good idea to check my compression. My compression was 190, 184, 190, 190. According to the vfaq oem compression should be 178psi. Does this mean that someone may have put 9:1 pistons in my motor before i got the car? I have a 95 so i wouldnt expect the compression to be at standard levels still. Anyone have any ideas?

 

[andymoraitis]

Based on your mods, you're still on the factory A/F maps, which are rich to keep the motor safe. Dollars to doughnuts says that you have heavy carbon deposits on the piston tops from so many years of running that way. Run a few treatments of Seafoam through the BOV line (it'll suck into the manifold) to clean out the motor internals. A compression re-test should show reduced compression that's more in range.

In case you have no idea what the hell I'm talking about, this thread should get you in the ballpark:

http://www.dsmtuners.com/forums/showthread.php?t=222686&highlight=seafoam

Good luck,

Andy

 

[spatulahunter1]

Based on your mods, you're still on the factory A/F maps, which are rich to keep the motor safe. Dollars to doughnuts says that you have heavy carbon deposits on the piston tops from so many years of running that way. Run a few treatments of Seafoam through the BOV line (it'll suck into the manifold) to clean out the motor internals. A compression re-test should show reduced compression that's more in range.

In case you have no idea what the hell I'm talking about, this thread should get you in the ballpark:

http://www.dsmtuners.com/forums/showthread.php?t=222686&highlight=seafoam

Good luck,

Andy

i know exactly what your talking about, i have a bottle of seafoam in the garage i ran it through when i first got the car but havent done it in a while so i will do that tommorow and post the results.
I could see the top of the pistons with a pen light and they are black like there is some carbon on top of them but its hard to tell how much when looking through the small hole for the spark plugs.

 

[andymoraitis]

Som carbon buildup will be normal, but if it accumulates, it can become quite hard. In that case, you may want to try something like pulling the plugs, pouring some in the combustion chamber and letting it sit over night. Vacuum out the excess and crank the motor over without plugs to get the rest out since a failure to do so can bust up the motor (hydrolock).

Once you burn it out, do some fresh plugs and an oil change and see what compression looks like. Just keep in mind that on your current A/F ratio, it will keep coming back.

 

[steel_3d]

When my head gasket blew I got crazy high compression in the worst cylinder. Either the fluid was sealing up the rings extremely well, and/or the fluid in the cylinder (which you could see shloshing around after a few cranks) took up enough room to increase the compression ratio.

Yours are very even, so it's hard to see how a head gasket would leak so evenly, but I thought I'd share my experience.

 

[blackGSX2g]

Motors with blown headgaskets don't always have poor compression. When my composite gasket went out, I had perfect 210 compression across the board.

 

[spatulahunter1]

Motors with blown headgaskets don't always have poor compression. When my composite gasket went out, I had perfect 210 compression across the board.

good point, but i know it does often tell you so i figured it was worth checking. Other than a compression test and finding oil in your coolant is there a way to tell if the gasket is bad without pulling the vehicles head?


I still havent had a chance to try to see if the seafoam changes my compression because on thursday i came down with the flu so my car had to be put off for a little while.

 

[Steve93Talon]

I had some oil in my coolant so i was worried that i might have a bad headgasket.

Overtighten any oil filters lately?

 

[blackGSX2g]

good point, but i know it does often tell you so i figured it was worth checking. Other than a compression test and finding oil in your coolant is there a way to tell if the gasket is bad without pulling the vehicles head?

What told me (other than the obvious signs) was a hydrocarbon test; found at Autozone/Advance Auto known as a 'block tester'. It tests your coolant for the hydrocarbons found in your exhaust, meaning there is a breech between cylinder and the cooling system (or you have a cracked head and are in more trouble than a gasket).

 

[larsrya8]

Vacuum out the excess and crank the motor over without plugs to get the rest out since a failure to do so can bust up the motor (hydrolock).

Are you sure you want to vacuum out the excess? The can says "Danger Flammable" right on it. One spark from the vacuum's motor with those vapors inside of it and.... fire!

Now, a hand powered vacuum pump (like a turkey baster) would be a much safer option.

 

[staticbrainwash]

How would a spark from a shop vac motor get all the way from the ground, down the suction tube (thereby defying the airflow), and into the motor? I'd say VERY unlikely.

 

[spatulahunter1]

Overtighten any oil filters lately?

Im not arguing, im more so asking cause im curious but how would that cause it? I only hand tighten my oil filters so i dont think they would be too tight

 

[spatulahunter1]

What told me (other than the obvious signs) was a hydrocarbon test; found at Autozone/Advance Auto known as a 'block tester'. It tests your coolant for the hydrocarbons found in your exhaust, meaning there is a breech between cylinder and the cooling system (or you have a cracked head and are in more trouble than a gasket).

that sounds like a good next step, my buddy works at autozone so he should be able to help me out with it.

I also had another bad sign. I just cleaned out the overflow resevoir to see if more oil would appear and after driving home from work today i decided to check it and i could hear boiling, i imagine that the gasket is bad and is allowing some air to get to the coolant allowing it to boil, either that or my t stat is bad but that still wouldnt explain the oil. Strange thing is that my temp gauge (oem) gets right to half way and doesnt climb any higher so i wouldnt imagine its overheating.

 

[larsrya8]

How would a spark from a shop vac motor get all the way from the ground, down the suction tube (thereby defying the airflow), and into the motor? I'd say VERY unlikely.

No no no... as you suck the stuff into your shop vac, it goes past the motor and whatnot. And it will create a very flammable vapor, which will be included with the air that cools the shop vac's motor (that's why the air coming out of the shop vac's exhaust port is warm).

Don't use a vacuum to suck up any flammable liquid. A guy blew up his vacuum trying the same thing with gasoline.

Yeah... having the spark somehow travel into the motor is very unlikely.

 

[arash15]

if you really want to find out whats going on, id do a leakdown test. it will tell you exactly what you want to find.

 

[spatulahunter1]

if you really want to find out whats going on, id do a leakdown test. it will tell you exactly what you want to find.

ive never done one before but im not sure if i would need to. According to the vfaq: "Why get a Leak Down test?

Doing a leak-down test diagnoses where you're losing compression
before you open up your engine.

If you did a compression test and your results are:

* more than 14* psi difference between cylinders
* any cylinder below 130* psi
* (these numbers assume a turbo engine)"

Im not losing compression at all, my compression is higher than normal and i think i have a blown gasket so i have no idea what a leakdown is gonna tell me

 

[Defiant]

Im not arguing, im more so asking cause im curious but how would that cause it? I only hand tighten my oil filters so i dont think they would be too tight

http://vfaq.com/mods/oilcool.html

 

[spatulahunter1]

http://vfaq.com/mods/oilcool.html

im definitely gonna check that out, thank you