Jcrow Posted April 1, 2005 Report Share Posted April 1, 2005 Take the head to a machine shop. My compression is about 150psi on all cylinders +- 3psi Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted April 1, 2005 Report Share Posted April 1, 2005 You really can't make a decision until you take the cylinder head off and see what's wrong. It all depends on how hard it hit the head. Quote Link to comment Share on other sites More sharing options...
R Dubya Posted April 1, 2005 Report Share Posted April 1, 2005 A buddy of mine snapped the timing belt in his Eclipse last year. He trashed 75% of the valves in the head, but it did not damage his aluminum head at all. It hit the piston and made a small mark in the top of it. I would guess that the pistons in that engine wouldn't punch through, it may be roughed up slightly.. pull the head and see. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 1, 2005 Report Share Posted April 1, 2005 i talked to the machinist that rebuilt my TGP heads today about the problem. he seems to think that the valve is probably not bent too badly; just enough so that it's not closing. that makes sense because i did see the valve & spring move at least some when i rotated the engine by hand with the new timing chain installed (valve covers removed of course). he told me that the valve might have left a small imprint on the piston top but more than likely nothing to worry about. he also seriously doubted the valve guide was damaged. he said a new valve should be around $15, and it would be less than $50 total to have it lapped and installed. i can replace all of the gaskets myself easy, and i think Fel-Pro actually sells head gaskets seperately. thankfully this is the front cylinder head, that will make my job alot easier and i don't have to pull the engine out. so....i should have it fixed this month sometime. i'll post some pics of the bent valve and piston top after i pull the head off (probably later this week). Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 1, 2005 Report Share Posted April 1, 2005 Compression variance should be no more than 10 percent. Probably had around 180-190 new so its still very tight, I'm sure there is still cross hatch in the bores with no real signs of wear. If a piece part came off when the valve kissed the piston metal fragments could score and gouge up that cyl wall, hope not 180-190!! are you sure it would be that high? :shock: and yes all of the cylinder walls had obvious crosshatching and were smooth as glass. the entire shortblock was very clean inside despite the 227,000 miles. i'm going to fix this problem and in the meantime either the 'real' LG5 sitting in my garage will start getting torn down & rebuilt, or i'm going straight to a newer low mileage LA1 3400 and run it on my TGP engine wiring harness, TGP injectors, and my NA 3.1/5-speed memcal. right now it's making more sense to go with the 3400 and start turbocharging it sometime next fall/winter. although, hopefully the engine that's in the car right now will be able to live with ~8psi until then. Quote Link to comment Share on other sites More sharing options...
riceca Posted April 2, 2005 Report Share Posted April 2, 2005 A buddy of mine snapped the timing belt in his Eclipse last year. He trashed 75% of the valves in the head, but it did not damage his aluminum head at all. It hit the piston and made a small mark in the top of it. I would guess that the pistons in that engine wouldn't punch through, it may be roughed up slightly.. pull the head and see. That is what you call an interferance engine :) Quote Link to comment Share on other sites More sharing options...
Dannymik Posted April 2, 2005 Report Share Posted April 2, 2005 man I wish I lived near you so I could learn a thing or two on this type of troubleshooting... Quote Link to comment Share on other sites More sharing options...
R Dubya Posted April 2, 2005 Report Share Posted April 2, 2005 Josh, do you have pictures of the pistons in the 'T' engine? I know there are differences, which might explain why the valves kissed, because our engines are not interference. I know that my TGP pistons were recessed, but I have no idea what the 'T' pistons look like. Quote Link to comment Share on other sites More sharing options...
Canada Posted April 2, 2005 Report Share Posted April 2, 2005 The front pulley isn't a balancer......its just a pulley. The 90 degree boys have a balancer. 0 psi.....sounds like you find why it was running rough/missing.....well, hopefully the valve didn't ruin the piston too. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 2, 2005 Report Share Posted April 2, 2005 well they look exactly the same to me... my LH0 piston tops: and my LG5 piston tops: Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted April 2, 2005 Report Share Posted April 2, 2005 The valve relief's might be deeper on the LG5 engine. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 2, 2005 Report Share Posted April 2, 2005 i serisously doubt it, i've inspected them both closely side by side. i think the only difference in the TGP piston is that they are a Mahle piston with a reinforecing steel band. not that i've had the pistons out of either engine myself so i may very well be wrong. the compression difference is in the heads, not the pistons IOW the TGP pistons do not have a deeper dish. from what i can tell the LG5 pistons are simply stronger an no difference in dish nor piston top design, etc. btw, neither the LG5 nor the LH0 pistons have valve reliefs. Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted April 2, 2005 Report Share Posted April 2, 2005 Well, what I meant by valve reliefs was the "dish" that they have in the center. My bad. Quote Link to comment Share on other sites More sharing options...
godofthunder Posted April 2, 2005 Report Share Posted April 2, 2005 gahhh i wish i had someone near me to help me change the HG on the cutlass....while I would still get the other car...could have this one runnning Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted April 2, 2005 Report Share Posted April 2, 2005 It's not to hard honestly how much have you done on your car before. I mean on a pushrod it can be done in a afternoon. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 2, 2005 Report Share Posted April 2, 2005 i can now say for 100% certainty that the pushrod GEN-II 660 is indeed an interference motor.... i got the front cylinder head pulled off now and there is only a slight indentation on the #2 piston (whew!). it's definately not bad enough to replace but i'll have pics up tonight or tomarrow of the mark it made on the piston. oh yeah, it was the #2 exhaust valve, not the intake valve like i thought it would be. sure enough it's stuck open! it didn't touch the cylinder wall at all, it just made a little mark on the piston top and obviously bent the valve stem. the wierd thing is is that i also found that piston #6 has a very very small valve mark on it as well, yet hole #6 had 150psi in the compression test. so right now i'm thinking i'm going to remove the rear cylinder head too just so i can check those 3 pistons out and have my machinist make sure that all 11 other valves are not bent. pics to come... Quote Link to comment Share on other sites More sharing options...
avitlqc Posted April 3, 2005 Report Share Posted April 3, 2005 thats a good idea. The timing belt broke on my 1995 Eclipse last summer and it bent all 5 valves. When i had the head redone they only replaced the bent valves, bad move. I rebuilt the block and put it all back together. When i started it for a minute it was running ruff so i had it towed to my local Mitsubishi Dealer and they had to redo the timing belt as the chilton manual said to set the timing mark off by one from where the factory puts it. To say the least my mechanic at the dealership informed me that I should always check with a factory mechanic before doing anything like that again. I also got told to always replace all the valves when you have a bent one because there is always a chance that one is bent and just not noticed. Anyways just thought that i would throw in my two cents. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 3, 2005 Report Share Posted April 3, 2005 well crap. i just pulled the rear cylinder head and it looks like the #1 intake valve made a small indentation on top of the piston....about the same as piston #2 but the valve doesn't seem to be bent (it's fully closed and compression was good). compression was good on every hole except #2 so hopefully the #2 exhaust valve is the only valve that needs to be replaced since it's the only one that's obviously stuck open. i'll post pics later today. meanwhile i gotta take these heads in and see if any other valves are bent. i guess i shoulda just swapped in an L67 huh? Quote Link to comment Share on other sites More sharing options...
R Dubya Posted April 3, 2005 Report Share Posted April 3, 2005 You may want to just consider doing all of the valves Josh, so you don't run into another situation like this. Just to be safe, you know? 8) Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 3, 2005 Report Share Posted April 3, 2005 hell considering the cost i think i should probably just start completely over with my LG5. i now have a turbocharged LH0 with 3 pistons that have slight valve damage, and at least one valve that is bent if not two more i'll probably just replace all of the valves, and throw some new head gaskets on this engine and run the bitch. i can use these heads on the rebuilt LG5 so i don't mind spending money on new valves. meanwhile i better start ordering new Mahle pistons, cam & other parts for the LG5.... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.