Engine Diagnosis

[FINOCJ]

My clutch problem and crank noise thread ended with me saying 'the worst that could happen is I blow up the motor'....well maybe it happened. I had to get towed out of Twin Cone this weekend and drug it home. Trying to figure out a plan for diagnosis. The engine runs but with a horrible misfire - its not backfiring through the carb but it sounds so far off that I don't really want to run it much. The misfire is accompanied by a good knocking sound, though not a 'heavy' or 'deep' knock that might be associated with the crank. Instead its more of a clack sound that might be associated with valve train - and the sound seems to come from high up on top of the engine block. There is also a sound that is a rapid 'spinning of gears' sound. Kind of a very fast 'clicking' sound. A main crank bearing may still be the root cause of all this. There was no obvious discoloration to the oil such as coolant due to a head gasket leak. Anyway all this is guessing...what to do next...

On the trail we checked the plugs, only 1 of the 6 looked to indicate good combustion; the other 5 were heavily fouled and overly rich (although some of that is due to my fixed carb jets that do not adjust for the high elevation). But even after cleaning the plugs the misfire was still horrible. There is also plenty of fuel getting there as well. So ...things I can do and check include, timing, spark, compression and vacuum. Trying to figure out what would be the best order minimize running and damaging it farther.

1) Start with removing valve cover and look for anything obviously screwed up. Turn engine by hand and look for valve movement (assuming I can differentiate valve movement from rocker movement).

2) Then compression check? Should I do this first? Doesn't require engine running (just cranking the starter) to see that valves are closing or stuck open?

3) I am trying to figure out a way to check timing without running the engine much - but may have to be done if nothing else is obvious. I may have a damaged timing chain or tensioner.

4) Go back and check the crank for more play if a bearing there has gone bad. Pull the oil pan and see what's going on.

5) Vacuum check can be helpful - but requires running engine.

What am I missing? Other things to check? Donations for the rebuild costs?

thanks

[Jim]

My two cents:
Pull plugs (and keep in order for comparison to condition to matching cyl)
Pull valve cover and give a visual inspect.
Compression check for each cyl - no need to add oil to each cyl (just keep throttle wide open). While cranking for compression check, look at camshaft / valve operation for unusual slop movement.

At the end you'll have:
plugs out, matched to cyls (I imagine they'll stay out for a bit)
compression test number for each cyl
visual for valve operation for each cyl

From there, you might be pulling the pan and removing end caps for bearing surface inspection.

only my two cents.

[Patrolman]

Ditto. Compression test to start and check the plugs to start. You put together a pretty comprehensive list to start. Timing chain, ignition timing, etc. Pulling the valve covers and oil pan are easy enough to do just to see if there is anything obvious.

You are running the Buick 225 right? I blew my motor in Utah in my CJ-6 years ago. It was belching blue smoke and going through oil like crazy. Never figured it out, just replaced it with a used one from a guy who rolled his CJ-5. Good news is those engines don't have a ton of demand, so they are cheap for a used one. Bad news is they might be hard to find.

[Spieg]

I'd lean toward the timing chain having slipped a tooth. Maybe turn the motor to top-dead-center and see where the distributer is pointing (compare to spec for your motor).

[FINOCJ]

Slow progress is occurring - not sure what it all means just yet. Pulled valve covers - all looks good to the untrained eye. Nothing obviously bent, cracked, broken, damaged etc. I guess its possible a pushrod is bent down below the valve area towards the camshaft where I can't see, but seems to be better things to check first. There is no brass in the oil in the valve area or on the dipstick. Ran compression test (dry no warm up): 135, 140, 138, 150, 140, 150 respectively for cylinders 1-6. Spec is 150-165, so some are a bit low but its an old engine and while not good its not the issue (just another one to put on the list for down the road). The main thing is that the compression test indicates a valve is not sticking open (correct?). I didn't get a chance to crank it and see the valve action with the covers off - sorry not enough hands to be in the cab cranking and see the engine bay. Maybe I can do that tomorrow.

Interesting to note, even though I quickly cleaned the plugs in the field the other day, and it only ran for a minute or so, all the plugs were soot fouled again. So I am moving to timing and spark issues. I am going to follow Spieg's advice and see if the rotor is pointing at #1 for TDC - I have mark on the distributor housing from a bunch of distributor and pertronix work I did a couple years ago. It may very well have had issues with timing chain - I've never seen mine but I understand the 225 ones often have a nylon portion to the either the chain or tensioner that can be a weakspot. If that looks good then I will try to verify I am getting spark to all the plugs. I put a new coil in last year but coils can be funny.

Back to my regularly scheduled job of grading papers all night...

[FINOCJ]

Patrolman previously posted:

[Patrolman]

If you want to watch the valve train move with the covers off, just put a wrench on the crank pulley and turn by hand. I typically do that anyways. Then I can see everything move in slow motion.

[Jim]

You could also "jump" the starter solenoid (the low amp side that powers the solenoid) to be at the engine bay and not behind the steering wheel.

A history less of mine: 1968 Ford 302. I replaced the timing chain - and it had the nylon components. One small chunk of plastic broke off and went into the oil pan (I don't recall if I knew of it happening before "the issue"). It ended up getting sucked into the oil pump where it seized the pump. That resulted in me calling that motor done and I put in a short block. Bottom line - check for any missing pieces of plastic that could be pulled into your lubrication circuit.

[78bj40]

Drop the oil pan and inspect anything that is visible

[Hypoid]

I am leaning toward spark. Take one of the plug wires and hold it about 1/8" from a good ground point on the block. Crank the engine and observe the color of the spark that jumps from to wire to ground. Is it yellow, is it blue???

[dieseldoc]

Timming.
Sounds like,you have a timming issue and the weak cylinder is making the miss fire even worse.

I have had chains skip in all sorts of jeeps....the older stuff had issues for sure.

You do have a few that are a bit lower than desired but the engine was running.

How does it turn when done by hand? Plugs out will be easier.

You can use the old stethoscope trick to narow down where the knock is comming from.
I used to have a mechanics scope.....was way nice for this type of work.

[FINOCJ]

Checked three things:
1) the rotor is aligned with #1at tdc so dont think it jumped a tooth.
2) I also checked slack in the chain by manually turning the crank back and forth and observing the nymber if degrees before the rotor responded. Its about 8 degrees which is ok.
3) finally got another set of eyes to help me look at the valve movement. I turned the crank by hand (which really can only be done from below while Jen watched the valves and noted that all the valves moved up and down at some point. So that combine with the compression test means I am leaving that alone for now. Also along those lines, my FSM indicates that my compression while a bit low, is perfectly within range when comparing across cylinders - specs require the lowest compression cylinder to be no less than 75% of the highest. Its just a bit tired.
So I guess I am moving to spark.

[Hypoid]

If the spark is good, move on to fuel....

[FINOCJ]

Hypoid previously posted:

[fredrok]

Hey Fino,
I'm no odd-fire Dauntless expert but I've been turning wrenches and troubleshooting a long damn time to include a shop foreman at a race engine machine shop in my past life. I've seen some weird *****. Would be glad to head over and give you a hand if we can make our scheds work out. Lemme know

One thing about the Petronix stuff is that unlike points, they are difficult to troubleshoot unless you have a "spare" to throw on.

[Jim]

My mind has been in the field of "this engine is making unusual noises". Is this a correct thought?

[FINOCJ]

fredrok previously posted:

[dieseldoc]

Sounds like you are doing every thing in the right order.
Member to K.I.S. it.....keep it simple

Keep pluging along you will find the issue.

[FINOCJ]

Update: cleaned up the plugs really well, checked the mechanical advance on the rotor - seems to be functioning - and put everything back together. It started right up but with a little rough idle and a loud clacking sound. I sprayed quite a bit of carb cleaner and adjusted the carb mix back for denver elevation which helped smooth out the idle a bit and checked initial timing is right were I set it (8*BTDC). There is nothing wrong with the spark or timing or anything like that. Actually, the engine seems to run pretty well except for the loud clack and just a bit of a exhaust 'puft' that sounds just a bit like a very weak misfire. I think its coming from the right bank but not sure. I put a rubber hose to my ear and didn't get much help except when I removed the oil fill cap on the right valve cover and put the hose above the open hole - then I got the really loud clack right in my ear. I did the same over the open breather hole on the left valve cover and it was there as well but not quite as prominent. I also get the sound but a bit weaker if I put the hose tight against the oil pan. I also noticed my oil pressure was a bit low - even for the normally low pressure these 225s run. It ramps up with throttle but wasn't doing much at idle. The oil is right at a quart low - its been time for a change so I haven't added any. That might be the reason for the low pressure?

Anyway, because I like to make more work for myself, and need some fresh oil, I decided to drain and drop the oil pan and take a look - this little project has brought to my attention just how oily everything is mostly due to a rear main seal leak so might as well replace that. Just got it off (was a PIA) and haven't inspected much. The screen at the oil pick-up has some metal in it - so that will be good to clean out. It looks like there is some sort of splash or protective pan under the crank that I will have to remove to see the crank bearings and replace the seal. That will be for another day.

As I generally like to have a working but flexible hypothesis - I am still concerned about the right bank valve train. This sound seems to be the loudest rocker or pushrod clack I've heard.

[Jim]

FINOCJ previously posted: