I've only got about 50 lbs of compression on 2 cylinders of my 2002 tl. This is after I changed the head gaskets. The car has been sitting cold, sometimes 40 or so degrees for 5 months. Will the low compression keep me from cranking it ? I'm having a hard time cranking it, but I'm not getting my coils to fire except intermittently. I've checked it with an inline style light that wires between the plug and coil. Sometimes with no fire at all while trying to crank. Then occasionally I'll see it light up ( I've tried it at different plugs, not the same one). If 50 lbs. is not worth trying I may call it quits and get someone to put it a used motor or something for me. I in need of advice before I work myself to death. Please help. The other cylinders are over 100.

 

overheat prob caused head gasket failure? long term overheating?- water pump bad etc?
this determines internal engine damage

comp tested with throttle open full to allow air in? several cranks to get good reading?

50!!!!! 100 is laughable, these are high compression engines,,9 to 1 and 11 to 1 (type S)comp ratio, Guesstimate 160-180 psi normal cyl compression

Who has an actual spec? max normal min'

If its got low compression it usually spins fast,,if it drags there is likely scoring-damage to the cylinder walls
Use fully charged battery
You replaced the oil with head gaskets and flushed radiator?

You can ck if its rings or valves leaking by taking a reading `dry`
then adding a few drops of engine oil into the spark plug hole- , turn over a few times- insert compression tester and retest-
thats a WET test, if comp rises its ring leakage-= the oil added some sealing abilty to the rings

to answer your question:sounds like used engine time

 

Thanks for answering 01tl4tl. Father used and it got hot and it cut off while driving. I changed head gaskets and water pump. That's what got me to this point. I was turning engine over with no upper intake on at all. Did not seem to drag. Oil drops did not make a big difference. I had the heads shaved and 2 intake valves replaced on the #1 cylinder. I forgot to turn the camshaft on the rear head to agree with #1 tdc and I bent them and had to take the one head back. But after that, I got a reading in the 175 range on that one cylinder.

 

with the heads off you could see any damage to the cylinder walls

have to tell you- from past experience, when a car stops running from overheat,,thats pretty bad,,the oil would be baked and trying to lube...
did you ck that and the coolant? which had the other fluid in it?

heads shaved,,performance mod while apart?,,or they were warped?
once I see warped heads: its got to have been a long term overheat prob, so other damage is likely
(dad probably didnt know the TL runs at just under half all the time, so 3/4 on the guage of an older car would be normal)

the good news is!!! you have all the parts to throw on another engine and have some extra power too!
Its still winter crashing season so plenty of auto recycler yards with TL/CL engines ready to go

 

another thought:

The TL has an interferance engine- as you know
Did the machine shop provide metal spacers, or you used a special double thick head gasket to correct for the removed metal, therefor reduced clearance to piston?
possible the valves took a beating and bending again--
A Cylinder `leak down test` with compressed air and guages will tell for sure where the air is flowing thru the cylinder

with oil not improving compression its got to be going past the valves- or the rings are totally shot on the pistons from the overheat

internal engine gurus- does that sound feasible??
Im thinking back several decades to datsun 510s on this one~

 

the heads should have come home with tags indicating the amount of metal removed
example: 2/32"

 

No metal spacers, but the machinist said he took very little off, he said he did not see much warpage. I did not use special gaskets, but I did use an oem gasket from Honda. It was much more expensive. I was told that was best. I did not see much water in oil drained from pan or from radiator. I saw some mix when I was taken it apart, some water on top of piston, but could have just been my sloppy workmanship(spillage). My father did tell me that he thought it was overheating for a while but could not pull over to miss work, even though he did. Oil stunk badly. So you are suggesting I use compressed air. How do you tell if its going through the block ? Can you tell through the dipstick or valve cover where oil is poured?

 

Putting oil into a low compression cylinder is test to determine if the problem is rings or valves. The oil goes down on the rings and forms a temporary seal, increasing the compression if they are bad. If the valve seats are the cause, then adding oil will not change the low compression result. The fact that one cause reacts to the oil and one doesn't allows you to confirm the problem. BTW, you should be seeing at least 160lbs across all cylinders.

In this case, the oil did not affect the compression so valves would likely be the cause and since you had the heads off and valves replaced, sounds like the probable source.

I've never seen a head gasket cause compression to be that severely affected given the gage reads the highest compression seen and I believe a bad head gasket would cause a very slow leak, not detected by a compression gage but would cause major overheating when run.

Of course there's the wacky stuff like a cracked block or a head gasket on upside down.

 

Thanks both of you. I am going to try rigging something to blow air into spark plug hole. I was told to take the rocker arm rail off so all valves close and try pressurizing each cylinder. Maybe I will notice something.

 

no,, its not that simple

you need a special guage set to add air to a cyl-
then using pressure guages and some listening tools- you ck where that air is going

Ive only done it one cyl at a time, turning engine so valves are closed at that cyl
ck wiki or youtube for cyl leak down

 

with a good `screw in` compression tester- you should see a slight increase with first few cranks then a final highest number

testing procedure will alter numbers- example- throttle closed vs wide open

 

Yea I meant screwing a hose with an air valve, not just blowing in the hole, sorry. I think the compression tester I used might even work if I unscrew the valve on the end I screw into the head. I might take off the rail that holds the rocker arms instead of trying to figure out how to get them on compression stroke. Just to see if air come out exhaust or out the intake. Someone suggested I may even have the timing off one tooth so that might not allow complete compression. I need to keep trying, I don't have an extra couple of thousand dollars these days.

 

Before taking every thing else off, make sure that ALL the timing marks line up. The belt should be put on in a counter clockwise position. If the marks dont line up its NOT right.

 

I only know about 3 marks (2- cams, 1-crank), they seemed on the marks. The counterclockwise I may not have done. I also heard that from a friend. Slack side issue. I'm not sure how much tolerance I have around checking the marks. They seem real close to my eyes. I also read that I should have turned the crank pulley around to check that mark and look in the small holes on the cam plastic covers. I did not do that. I'll be going back over that stuff this weekend. I am appreciating all the advice. This is supposed to my daughter's car by May 2. She turns 16.

 

01tl4tl re: your post #11. I checked it with no upper intake at all. Turned over with starter several times. It hit highest point after about 3 or 4 turns then stopped. No upper intake matter?

 

as long as the heads and valves were on- thats internal compression

fsttyms1 may be on to something with a cam being off a tooth, that would explain a lot.
Get a magnifying glass if needed but those marks do line up!!
ck out diy and gen3s which has excellent pics to guide you

as for where air may leak--its the exhaust valves in danger when piston contact possible.
you already tested oil method so its probably not rings

lets hope a full check and adjust cam timing will solve all issues!

 

I've got air blowing up through the intakes pretty strong on front head. I took off the rails that the rocker arms are attached to. I sent air through the spark plug ports and could easily hear and feel the air through intakes, but hardly any through exhausts. I guess I'll take heads to have valve job.