I have no idea. Very complicated problem. Very weird.

IndyBlk5.0

New Member
Nov 24, 2003
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New Whiteland, IN
Well if you all remember, I had my motor rebuilt to solve blowing head gasket problems. I got the motor back, and seemingly from startup, like the last two times, it had a problem with compression. So I tested it, came back with 60 compression in #7 and mid 80's for #8. Well great, the two cylinders that were blowing headgaskets last time i built the motor are acting up agian.

Now, I have no overheating, no exhaust gases in coolant, no water in oil, no oil in water.

Week later, (today) ive drove it for a bit, and it seemed to get better, i did a compression test on #7, well its 75 now, and #8 is up to 118 with the rest of the cylinders. So i go take it on a ride, keep in mind my car has had a noticable miss and vibration in it since start up. I drive down to a town about 15 miles south of us... Half way there, i feel a miss, a miss agian, and then a boost (as in, more power) Well hey, what the hell, my motor doesnt vibrate and goes through the gears smooth now! So i get it home with a smile on my face, give it a little victory rev, then i notice the nice blue smoke plum it lets out.

So I did another compression test, same results as earlier in the day, but instead of the plugs having a light pink tenge like before, #7 was the same pinkish color, #8 was pitch black. So I start up the motor, and hear a knock from hell. Check oil, i lost over a quart of oil after 15 miles, (I am assuming i started loosing oil from when this weird miss and boost thing happened) So i get a nice hollow knock with lifter tick. Died down once the oil got up to the heads.

Its parked in the garage, i just payed 1000 dollars for my engine rebuild from a local machine shop... What just happened to my motor? :nonono: :shrug:
 
what kind of rebuild did they do? you better take it back and make them redo that crap. they might have bent or messed up the ring gap or the ring on those cylinders...or put the wrong ones in it. did they bore the cylinders out?
 
WHY WHY did you mess with the engine after someone else rebiult it!
Hope they take it easy on you and not blame you for how the engine is acting up now.
Just a note: When i did a compression test on my engine, none of the cylinders were under 170.
My method of compression testing is:
1.Engine close to operating temp
2.All plugs pulled
3.Fuel pump off
4.Throttle body held wide open
5.Cycling engine 5 times per cylinder, each cyl tested twice.
 
118 is low. and you should not be getting the results you get. I would take it back to the machine shop. They obviously wernt paying attention to detail. Engines need looks of attentions and good small details the more you pay attention to these details the more power and longer time you get out of the motor. (Thats what blueprinting is all about Attention to detail)
 
Listen take the motor back out and bring it back to the guy and tell him what is going on. The motor should be under some warranty. Most rebuild shops do that. Give you like 3 months and 3000 miles.


What it sounds like is that your haveing a ring problem on the number 7 cylinder. That is why it is not holding any compression. It is getting blow by. If one of the rings is not set right, or it was not cut right. There is a good chance that the ring can cut into the block, and then your block will be just a big paper weight. Have it checked out asap. Becasue if you keep driving around on it, there will say that you did not break it in properly, and then your screwed out 1000 bucks.
 
All I can say is something is really screwed up in that engine man. On a fresh engine your compression should be 160+ depending on your compression ratio of course. Even a 8.5:1 Compression engine will have more than 118. As mentioned above I'd say it's something to do with the ring's... has to be. Take it back and tell them to fix it proparly whether they like it or not. What ever you do, don't run it anymore.
Good Luck, Hopefully you get her running good.
 
Indyblack - take it back to the folks that rebuilt it for you before anymore time passes. That simple. If you're gonna do anymore self-diagnosis, start by pulling the codes to see if there's anything else that's contributing to the running condition.
 
Thats what I told him in the first place. But he said that compression was normal and it depends on the cam blah blah, the heads have been milled a few times, i should be more at 10:1 compression. I know i should have higher numbers besides 120 acrost the board.

He blamed my whole problem on my egr not being hooked up, and my induction. Thats bs. That has nothing to do with the problems im having.
 
IndyBlk5.0 said:
Thats what I told him in the first place. But he said that compression was normal and it depends on the cam blah blah, the heads have been milled a few times, i should be more at 10:1 compression. I know i should have higher numbers besides 120 acrost the board.

He blamed my whole problem on my egr not being hooked up, and my induction. Thats bs. That has nothing to do with the problems im having.

If hes not gonna fix it, i feel a lawsuit coming on
 
also i bet that he didnt cut the ring right, so it was set wierd and all the friction was grinding into your block, hense the missing.. The oil ring probabally finally gave way and chipped/broke which is why its burning alot of oil. And now that something is out of place it probabally has alot less friction which is why it is runing smooth..
 
SLiM JiM 156 said:
also i bet that he didnt cut the ring right, so it was set wierd and all the friction was grinding into your block, hense the missing.. The oil ring probabally finally gave way and chipped/broke which is why its burning alot of oil. And now that something is out of place it probabally has alot less friction which is why it is runing smooth..

thats what im thinkin happened also. the guy didnt gap the rings right and its getting a lot of blow by...and the oil ring is probably gone
 
Dude something is wrong with SOMETHING that they did. My 86 with 140ish now with a cam that's all wrong & not degreed in is still pushing 135-140 on all cylinders with probably a hair less than 9:1.

Somethings fugged he needs to fix it.
 
Like said before, something is wrong, sounds more like it's the intake valve sucking oil because the oil drain is clogged or the PVC system is drawing way too much oil laden air into the upper intake (#8 ends up with all the oil from the PVC system). The missing was most likely the plug being fouled and you finally got it hot enough to clean t self off. Black is also deceptive. Make sure it's not getting gas fouled from a leaking injector (probally not, but possible).

Your oil is going somewhere.

Jamie
 
I saw a rebuilt 350 lt1 motor do that before..a Mechanic that worked for my dad rebuilt it and I was there when He started it up..it was using a lot of oil and low compression..He ended up tearing the motor back apart and the problem was the rings..there are I believe 4 rings per cylinder and the mechanic didnt stagger the gaps in the rings..which in turn , gave the oil and compression a easy way out of the motor..That might be the problem or He didnt use the right rings for the car..maybe when He bored it out 30" over He just used rings for a stock 302..Who knows? Hope you figure it out and get it fixed..FOR FREE!!!