I just ran a compression test since my tpi motor is popping under acceleration and running crappy and after onl checking the front two driver side holes the one holds at 180psi and the other leaks down to like 60 or 90 and i think it stops or maybe it didnt anywyas it loses psi pressure so is it a blown head gasket or blown piston, i am only 16 btw and now i have $300 and a pos s10 with a 1987 tpi motor in it story of my life.

 

Oh i did forget to put throttle to wot it was just shut during test but still the damn thing loses pressure, so im thinking blown head gasket.
Also it seems to smoke whitish black color out the maniflods (no exhuast hooked up)

 

Go try it again. All plugs out, and throttle wide open.

 

Alright throttle wide open and it drops to 90psi still like before and it seems to hold steady at the 90psi after the rest leaked out

 

Compression test is only good to isolate a problem cylinder. A leakdown test can determine a probable cause for the bad cylinder. Could be a bad piston/rings. Could be a bad head gasket but that could also show up as a coolant loss. Could be a burnt valve since you said it was popping..

Since you already know what cylinder(s) are bad, start saving up for repairs. $300 won't get you very far for anything. Although repairs are not that bad if you have mechanical knowledge and tools, it may be a lot easier to just buy a complete replacement engine. Even a bone stock replacement engine is better than none at all. The cost to do a complete rebuild if that's what's required will be more than it cost to buy another engine.

Don't expect any kind of quick fix with some snake oil remedy.

Do a compression test on all 8 cylinders with the throttle at WOT and all the plugs out.

 

Im going to have to decide between parting it out, selling it like it is, and buying another motor and attempting my first motor swap, or replacing blown head gasket, and i choose to kill my self so yay that was easy, seriously though i dont want to spend the money and swap in a slow motor and it only be worth like $1800 running when i could just sell it like it is for around $800-$1300 so ill think about checking the other cylinders tommoro but likely wont as id have to let it warm up and alot is already disconnected to run the comp test.

 

Ok so what kind of block with heads already on it will this tpi setup i have work with so i can just buy a complete block with heads up to the intake only, i found one for $250 from an 80s chevy

 

At least verify what the problem is before you shoot it in the head. Might be a simple gasket, valve, or rocker adjustment problem.

 

Times 10 and I agree.

These guys will tell you that I have bought a ton of used stuff and if you don't know where to look and what questions to ask,you could likely be buying the same thing or worst.

The cheapest answer over the long run is one which you re-built yourself.That is the reality.........

 

well considering that out of only checking 2 cylinders for comp, and one leaked pressure,and the motor smokes, and it has loss power im almost certain its something like a bad piston,ring, or head gasket so thanx everyone but im cutting my losses and selling it for $1200 tommoro or trading for a 1980 dodge d150 with 318 v8, so if i do a compression test and they all are 10% within each other the compression is good and motor to rite because it was swapped in this truck and he said that its not firing and its a $1000, just need to know what to check for on cars when buying them to check the motor over the most possible, thanx very much everyone

 

You still don't know why those cylinders leaked down. A leakdown test can determine if you have a bad head gasket or a bad head. Either way the head will need to come off. Doing proper testing on all the cylinders may make the decision if the engine is worth repairing or needs a full rebuild or replacement. Simply budgeting for a head gasket then finding out after you tear it apart that you have a melted piston or burnt valve will blow your budget.

 

You can only "teach" the willing.....................