89 7mge odd engine problem

amped12345

New Member
Aug 10, 2012
46
0
0
League City, Texas, United States
My 89 died randomly one day , and it couldnt get it to start again, after many weeks of poking around and effort . I finally narrowed it down to lack of vacuum happening on the AFM. shutting the fuel pump off So i changed all the intake gaskets and i bought new air intake piping. Now the car starts runs and will stay running. but it lacks power i didnt really test it on the road i just backed it and drove it forward in my driveway but typically when i push on the gas pedal this car will jump forward in my driveway. and also while the engine is running it makes a very odd sqeak noise and its not coming from the belts it sounds like its coming from the top or back of the engine. Im going to do a compression test on it to eliminate my fears of my very well built engine being broken and post a video of the engine running. But other then that any Ideas?
 

Black Cat

Member
Sep 11, 2009
62
0
6
Fort Bragg NC
Is the squeak rpm related, or is it the same no matter what?
How did you confirm that its not coming from the belt?
I agree that a compression check is always a good thing to check but it doesnt sound like the original cause of the
engine turning off would cause your engine to break.
also 5 speed or automatic?
 

amped12345

New Member
Aug 10, 2012
46
0
0
League City, Texas, United States
Well my car is automatic, and i have no idea what would be the original cause of it stopping i was driving it at full power going 45mph on the road and the engine just cut off and wouldnt start , however i will say this randomly at stop lights and stuff the engine started idling really badly, like 200-400 but if i gave it gas it would be perfectly fine. so i was trying to get it home asap and it died, i dont see how though it was good on oil, and everything only thing i can think to affect it was the cold. and the sqeak was coming from the engine i took off all the belts, and started it . the squeak does get louder when you rev the car it sounds like a really broken engine, and once you rev the engine to 4,000 rpm it would die . and i did my compression test, i got 120, 120, 90, 0, 90, 120 , however i will admit the compression tester i got was really ghetto cause it didnt quite fit in the spark plug hole and if you tilted it it would leak air, i had to do it multiple times on some pistons to even get a reading , so i imagine those numbers arent accurate but a general idea, i felt that it would be really weird that i just get 0 on one piston valves would have to be stuck open or something. SO i took off the engine head, hoping a keeper or something fell out , but no all valves looked in tact i havent had the chance to pull them out to see if it got stuck and maybe bent , but so far everything looks perfect i cant find a problem with the car. and i looked at my pistons and stuff just even though the block was taken to a shop, and everything inside the block is brand new, pistons , rods, rings, crank, bearings, oil pump, everything... So what could it be
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
You say everything in the engine is brand new? (pistons/rings/bearings/oil pump/rods and crank?)
Does that mean you just had it rebuilt? If so, then someone screwed up bad. The squeak could be a bearing but that is usually a grind followed by "slapping" as it loosens. At that point, most of the engine is shot..

A little info would help regarding history of the engine. When was it rebuilt? Who assembled the block and who assembled the head? What was done to prep the surface? What head studs/bolts were used.. etc..
I thought a 7MGE correct compression is normally 150 psi across all 6 (I may misremember that... )
 

amped12345

New Member
Aug 10, 2012
46
0
0
League City, Texas, United States
History on the engine it had a rod knock bc the previous owner ran it dry , so i tore the engine apart, took the block along with the main caps and rods to determine what bearings i would need. to the machine shop along with the timing cover front plate, and they said the block was in perfect condition it got resurfaced and cleaned up , and i began ordering my parts , ( new oil pump, Sealed power bearings, new rods, crank, and arp bolts for the rods, along with pistons rings and bushings, and i assembled it . ive put together many engines before and this is the only one to actually fail on me. i suppose my downfall would be my ebay Yonaka Headgasket and only doing the valve stem seals on the head ,along with not replacing all of the coolant hoses so ocasionally some would bust or leak causing my supra to over heat i would shut the car off immediately , and fix the problem. the car was running for almost a year now before it died, after it was rebuilt.so thats the history , As of now after taking the head off i was concerned about internal engine damage, so i rotated the engine and the crank spins freely making no noises and the pistons move up and down. or anything. the sqeak was removed with the head. when taking out the cams i noticed some scoring on the second two bearings in the front. so that might be the culprit for my sqeak. but as of now im getting the head checked . and springs tested along cleaned up and such i also plan to replace every coolant hose. any suggestions on head gaskets if it all checks out?
 

Grandavi

Active Member
Sep 25, 2008
2,663
5
38
Calgary, Alberta, Canada
Firstly, remember I am not a mechanic or qualified technician.. just simply a fellow Supra owner with comments....

Okay... from what you said, you were rebuilding the engine properly (other than cheaping out on the one area you need to do right... the head gasket).

It sounds like the headgasket was bad just from your compression.. (should be minimum 98 psi or max 156 psi if I remember correctly and should be less than a 14psi variance between cylinders...) and you ran it and it overheated (btw.. when a hose blows, that doesn't necessarily mean your engine overheated.. if you shut it off right away. Hot air will make the temperature sensor spike).

You definitely want to look closely at your head though, especially if the squeak came from the cams. I dont know about your skill level for rebuilding. It just looks like a simple rebuild needed (rebuild the head, lap the block.. get ARP head studs or bolts and put them on exactly as they tell you). I am using a Cometic Metal headgasket on my 7MGTE. I think the OEM HG is fine for a 7MGE, however if you do the metal HG, you will be far less likely to ever need to retorque or worry about a BHG. That's the simplified version...

However, it sounds like you were running for a while with a bad head gasket. Did you notice coolant in the oil or oil in the coolant? From the compression test I would guess that your oil was contaminated with coolant. If so, your going to want to look at your crank and bearings to make sure no wear occured from bad oil. You dont want to rebuild this a third time. My bearings were wearing due to being installed "dirty", but you couldn't tell from spinning the motor. We had to pull the engine to check the bottom end. In the end, I bought a new shortblock.
 

amped12345

New Member
Aug 10, 2012
46
0
0
League City, Texas, United States
yeah im defintely getting the head checked by professionals and rebuilt if i can salvage it , the block has already been resurfaced , and i don't really want to pull the lower half of the engine, and no there was no coolant in the oil or mixing of anything, but i will take the oil pan and check for things, and the oil is its natural color. all ive ever really noticed is my hoses busted. on occasion and if i replaced it , it would never break again