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Compression Conundrum
https://slantsix.org/forum/viewtopic.php?t=63233		 Page 1 of 2
Author:  62alumblock [ Mon Jan 28, 2019 11:41 am ]
Post subject:  Compression Conundrum
Hello everyone, I am still trying to get my 62 Lancer going. I got the junkyard engine in there and going, but realized that the bearings needed changing (oil had metal dust in it) and took it out again. Fixed that up, put it back in, got it running (rough but ok), drove it gently up and down the street, let it run sitting, then took it to 60 on the freeway, which felt pretty good, got off and when I slowed to a stop it died and has not started since. It did not blow smoke, the thermostat was reading hot but not in the red (water temp held at 120F while running (maybe the new temp sensor not calibrated to old car?)). I tested it for spark, which it had, and blasted starter fluid, but no start. I tested compression and got 60PSI on one of the valves, but wasn't certain if I was doing it right so I took it to a shop and they told me the compression was reading from 10-60 in all the cylinders. So then I took off the head and had the valves vacuum tested, they were fine. The cylinders looked ok, a little ring around the top but not too bad. The head gasket itself seemed fine. The machine shop said the thing looked good.
I put the thing back together, made sure TDC was synced with Compression stroke and rotor (#1 at TDC with valves closed and rotor pointing towards #1 plug wire). I put an inline plug tester and that is showing a regular strong spark. The engine does have pertronix (sp?) ignition. There is 12v to the coil, and 10v from the coil to the dizzy when key is on. There is 12v between the battery and the head, so the ground seems good. When the rocker arms are not pressing the valves open there is a little bit of play so that tells me the valves are not constantly being pressed open.
When I try to start the engine, there is a minute amount of sputter right off the bat, then nothing. I've tried to move the dizzy back and forth a tooth, as well as put the plug wires advanced to every spot. When #1 wire goes to where #3 should be, I get some kind of hiccup backfire intermittently.
So, it's probably the piston rings. But for them to all go out at once? Maybe there was a stop leak on them that burned out after the first freeway drive. The new plugs were very dirty after that first drive. Is there anything I should try before I pull the motor out for a 4th time? There are new plugs in, I've blasted starting fluid, and nothing. It seems like I should get some kind of combustion.
Any thoughts? Thanks for whatever you've got.
Author:  THOR [ Mon Jan 28, 2019 12:07 pm ]
Post subject:  Re: Compression Conundrum
From the way this issue is presented, it seems as though we need to get a baseline first. I'm more concerned with making sure your engine has it's compression issues sorted out before delving into the dirty plugs.

1. What is your valve lash set to on Intake and Exhaust? A "little play" is not sufficient enough of a measurement.

2. What is your timing set to? "Moving it back and forth" again is not sufficient enough of a measurement. I would strongly suggest doing a "Stage zero" tune, and set everything to factory specification.

Set valves to .010" intake and .020" exhaust. Set timing to 10 degrees BTDC and make sure the rotor is pointing at the correct plug wire.

The reason you get backfiring when swapping wires and moving the distributor a tooth is because you are creating spark too late or too early and the fuel is combusting when a valve is open. It would be a good idea to check whether the timing chain has stretched as well. This can be done fairly easily by leaving the distributor cap off and rotating the crank back and forth. If there is more than a few degrees of crankshaft rotation before moving the distributor rotor, you may have a stretched chain, which will cause the cam to be out of phase.

A leak-down test will be required to verify the integrity of the rings without pulling the engine. https://www.youtube.com/watch?v=WgrfT0LFMhc

~THOR~
Author:  62alumblock [ Mon Jan 28, 2019 1:16 pm ]
Post subject:  Re: Compression Conundrum
If I spin the fan backwards (rotor goes counterclockwise), there is several degrees of spin before the rotor spins. If I spin it forwards, it seems to spin immediately. I assume there should be no lag either direction.
Author:  62alumblock [ Mon Jan 28, 2019 2:35 pm ]
Post subject:  Re: Compression Conundrum
Actually, the harmonic balancer will spin about 1" each direction before the rotor moves.
Author:  Rick Covalt [ Mon Jan 28, 2019 2:39 pm ]
Post subject:  Re: Compression Conundrum
1" is a lot of movement. Is it possible it had the "plastic" timing gear in it and it has jumped a tooth or more and is out of time? If it was running well, it had some compression. If compression went away and it won't start it very easily could be out of time.
Author:  slantzilla [ Mon Jan 28, 2019 3:21 pm ]
Post subject:  Re: Compression Conundrum
Timing chain skipped.
Author:  jcc [ Mon Jan 28, 2019 4:39 pm ]
Post subject:  Re: Compression Conundrum
Quote:
Timing chain skipped.
Lost Oil Pump/gear, Wiped the cam lobes, Slants do run without oil pressure, for awhile, all the other suggestions here are more likely and easier to resolve. Keep your fingers crossed. And the compression issue concerns me the most as to where your problem resides.
Author:  Dart270 [ Tue Jan 29, 2019 5:16 am ]
Post subject:  Re: Compression Conundrum
Check valvetrain and lash settings by factory procedure.

Lou
Author:  THOR [ Tue Jan 29, 2019 12:08 pm ]
Post subject:  Re: Compression Conundrum
Quote:
Actually, the harmonic balancer will spin about 1" each direction before the rotor moves.
That is quite a lot of movement.

My suggestion is to pull the harmonic balancer and remove the front timing cover. I bet you'll find a very droopy chain and worn cam sprocket teeth. Fortunately, a replacement set isn't difficult to obtain. A cam that has come out of phase by jumping teeth will surely have a compression loss and it will cause an otherwise well running engine to fail.

~THOR~
Author:  62alumblock [ Tue Jan 29, 2019 7:59 pm ]
Post subject:  Re: Compression Conundrum
You all are pretty good. So I took off the chain cover and found the chain had at least an inch of slack. The cam sprocket bolt was actually loose, enough so that the sprocket was rotating back and forth on the, digging out a sliver of aluminum. Some sprocket teeth had a small divot in them. I ordered a new sprocket and chain. Should there be anything else I check or do before moving forward?

Also, the little niblet from the balancer puller tool is now stuck in the crankshaft. Torch?


Chain lifted about an inch
Image

Back of cam sprocket with aluminum shaving
Image

Teeth with divots
Image
Author:  Dart270 [ Wed Jan 30, 2019 3:59 am ]
Post subject:  Re: Compression Conundrum
Dang, sorry to see that. Loctite and overtorque by 5-10 ft lbs.

Lou
Author:  Charrlie_S [ Wed Jan 30, 2019 5:36 am ]
Post subject:  Re: Compression Conundrum
I'm hoping you didn't mess up the threads in the crank. A bolt is not required/used on most slants, but the threads are used to install the damper (it shouldn't be hammered on). Can't really suggest a way to remove the piece.

When installing the new chain and sprockets, if at all possible you should really degree everything, as the timing marks on the new parts may or may not be correct.
Author:  62alumblock [ Wed Jan 30, 2019 10:46 am ]
Post subject:  Re: Compression Conundrum
I read Dan's post on how to degree the thing, but it the pictures were not there and it seemed a little complicated. Any other resources or tips?
Author:  THOR [ Wed Jan 30, 2019 11:09 am ]
Post subject:  Re: Compression Conundrum
Quote:
You all are pretty good.
We do our best! :D
Quote:
Should there be anything else I check or do before moving forward?
Make sure you get the washer back in correctly behind the cover and front pan seal on correctly, otherwise you will have a significant oil leak.
Quote:
I'm hoping you didn't mess up the threads in the crank. A bolt is not required/used on most slants, but the threads are used to install the damper (it shouldn't be hammered on). Can't really suggest a way to remove the piece.

When installing the new chain and sprockets, if at all possible you should really degree everything, as the timing marks on the new parts may or may not be correct.
Charlie is absolutely correct. That being said, I've found it difficult to really mess up the threads in the hardened steel of a forged crank. The threads may be fine. I would suggest a set of Vice grips to wobble it out. Failing that, some light tapping from multiple directions with a dead blow hammer may rock it loose. I wouldn't suggest using a torch. For balancer reinstallation, I've had to "tap" them on before, but as Charlie stated, it is not the correct method and doing it improperly can cause damage to the thrust bearing and crank snout.
Quote:
I read Dan's post on how to degree the thing, but it the pictures were not there and it seemed a little complicated. Any other resources or tips?
Once you have the new timing set in your hands, it should become a lot more clear what needs to happen. I've installed many by just lining up the dots, but your mileage may vary. I've always used Cloyes replacement sets.

Hopefully someone can fix the photos that are missing from Dan's post on how to degree a cam.

~THOR~
Author:  62alumblock [ Wed Feb 06, 2019 3:50 pm ]
Post subject:  Re: Compression Conundrum
Well she's running pretty good now. Though, I found a little oil weeping from where the head meets the block on the plug side of the engine. Hopefully re-torquing the bolts will stop it. Also, it's running a little hot, like half way to the red. Is there a chance I have a mismatched car/temp sensor? As if the 62 car is not calibrated to the 70somethig motor? I thought I read something about this long ago.

Thanks again for everyone's help. I am planning on driving the thing to the mechanic that told me I needed a rebuild and ask him if he wants to know the easy diagnostic that clued me in to the actual problem. If he gives me my $200 back I'll tell him.
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