engine woes

[shootist]

ok so after a 2 year resto and much help from members here
on my way to the trucks first show
then all of a sudden....all heck broke loose under the hood......
banging,knocking crunching it was an alarming to say the least.
Temp was fine (new sender and gauge the day before) and thermo gun confirmed
temp, oil pressure was fine as always 30-33 pnds at idol and about 38-40 pnds road speed
Any how had her towed home and she sat for 8 hrs or so
I decided the only way to get it the garage was to drive it in...
started right up no issues, there was a faint "Knock" for lack of a better term
at idol when throttled up to move it got louder with the higher rpm but nothing like the racket earlier that morning.
after some listening around it was determined it was coming from the rear bottom of the motor. Using the old screwdriver to the ear trick surprisingly the oil pan and block were quiet..... but the bell housing was knocking away, being a "cyclical"
type sound figured maybe a bolt backed out o the flywheel....nope all looked good
pressure plate and all looked good also...throw out bearing was on its way out but I knew that.. next did a compression test all was pretty good except for #6 which I also knew someday I would have to do a ring job (soon as I figured out how) . I then wet tested and compression was fine.
Next I drained and strained the oil and found nothing...next I used a bore scope to look around and everything looked ok (Ive never seen the inside of a motor)
So I removed the oil pan and found copper all over the shelf in the rear of the pan directly below #6.. I looked around with a light not knowing what Im looking for or at and all looked brand new just about except that the #6
connecting rod upper bearing at the piston appeared copper colored and all the others are silver colored so Im guessing this is the issue based on what I found in the pan....
Thoughts? suggestions? any methods of verifying this is bad? can I change this bearing and do the rings
with out removing the engine? (removing it is beyond my capability)
and no I have never done anything like this before kinda wish I had at this point it was a real kick in the pants after all that work
.....lol anyway as always Im hoping to get some answers

 

[Oldfart]

It appears you have lost the wrist pin bushings. You can remove the head and take out the #6 piston to effect a repair.

 

[shootist]

Oldfart thanks for reply.
Im wondering if I should also replace the pin and the lower bushing/bearing also
For the sake of thoroughness while I have it apart, if in fact this is the only issue I find?
Your thoughts?

 

[ralbelt]

Pull the engine and do it right. You will have the head and bottom off any way. You need a ring job, throw out bearing is bad. Do it all at once.

I just had a jeep [not MV] engine total rebuild at an engine shop in West Warwick, still have to put it back in.

I could offer some help in a month or so puling the engine. After I get back from Ga and Fl.

 

[ke6rwj]

i would certainly measure them and check for scoring, but these are usually in sets, and once you get in there..... its amazing how quickly you end up with the engine in pieces...

Im a bit worried that the cylinder will be scored, you can certainly replace bearings and rings with it in the truck, but to do it right, you need to have the block serviced also.. honed, etc..

maybe the m37 tolerances are more forgiving..

replace the needed parts, and see how it goes.. thats what i'd do, especially since pulling the eng is out of scope for you.

 

[Oldfart]

Shootist,
As my handle indicates, I have been around a while and my view of what to do has changed as I aged. When I was first at vehicles as a teenager, money was scarce and I just fixed what was necessary to keep things running. Now I would be inclined to pull the engine and rebuild it. The fact is you will have to pull the head to pull the piston to fix the wrist pin. More likely the piston will need to be replaced. You can break the cylinder glaze by using the old piston and some valve grind compound (assuming the bad wrist pin has not caused cylinder scoring.) The Dodge 230 L6 engine uses offset rods and over time they tend to wear the rod bearings at the edges. It makes sense to replace the bearing on at least #6 since it had the added stress of a loose piston. If you are going to go that far, then it makes sense to check the rest of the rod bearings. Given the probability of finding other things to fix and already needing the most expensive gaskets out of an engine rebuild kit, you might as well go all the way. It will cost more in the short term, but it will be cheaper in the long run ~~ Again, this an old man opinion based on my economic ability at the moment. If the economy keeps on like this for another year, I will probably opine that you should remove the #6 spark plug wire and back the valve adjusters off so as to keep both valves closed (or at least the intake valve.)

 

[DieselBob]

I would agree with ralbelt on this. Pulling an engine is fairly simple and you can rent the hoist pretty cheap if you don't have access to one. At this point there is no real way of telling the amount of copper contamination in the bearings and oil system. The only real way to do a through cleaning is to have it tanked and roded to be sure all the oil passages are clean. Otherwise you just take a chance of pumping garbage through the rest of the engine.

 

[Hal_VT]

A long time ago I had a 56 Dodge half ton with the 230 engine (similar to, but not the same as the M37). I had the head off to replace the head gasket, and discovered that it had had some problems with a wrist pin, which had obviously been replaced before I bought it. There was a gouge in the cylinder wall on both sides as if the pin had bounced back and forth for a long while before it was repaired. I ran that engine for a long time before I could afford to replace it. It always ran well, and had good power, but it did use a little oil.

 

[shootist]

Wow invaluable comments! thanks for the replies.
I had in the back of my mind I may have to pull the motor....
I was and am trying to avoid a complete rebuild do to
$$$ shortage.
Its not the fact of having or attempting a rebuild (just dont wanna!)its the cost....
if I had the $ I wouldve got the back hoe and ripped it out the next day.
I know that attempting to replace just the broken part is probably a short cut
that shouldnt be taken...........
I tend to be very thorough and its killing me not to be able to do this 100%
I did make a typo in my first post- its the # 5 cyl which I have 131 pnds of compression. I took some pics incase someone else had the same issue
and wasnt sure what they were looking at either. for those that dont know
the first 2 pics are the oil pan shelf, 3rd pic is the rear wall under #6cyl, 4th pic
is in bottom of oil pan under shelf, (holy sludge.....)
5th pic is #6 CYL with what appears no issues, 6th and 7th pics are the culprit pics
in #5 cyl and the 8th is well you know....

 

[Oldfart]

At this point, there are still unknowns that would impact what is required for a repair. The do nothing further approach would be to make it basically a 5 cylinder engine (pull the plug wire and try to keep the intake valve from opening.) Since you have access to a bore scope, you could try to check the cylinder walls to see if you have scoring. However, any wrist pin repair will require the piston to be removed, so the head will have to come off in any case. You will probably need a ridge reamer to remove any ring hook so the piston will come out. If you are lucky and there is no significant scoring of the cylinder wall (may be the case since the compression is high there, you might be able to press in new wrist pin bushings if the piston has not gotten ovaled in the bushing holes. If the piston rings are ok then it is possible to repair the wrist pin and reuse the old rings. If you can reuse the old rings, you can consider avoiding having to break the glaze on the cylinder wall. I would try to avoid rotating the rings in the piston (reinstall the piston with the rings in the same positions.) You really won't know how minimal you can be until you find out the extent of the damage. ~~ The bushing frass is a problem and you really need to clean all of that out that you can. Copper is malleable to a point, but getting that crap stuck in the bearing lead will accelerate bearing wear rapidly.

 

[WarrenD]

Bummer. I think I'd give Bob Stahl a call. He's in Wrentham, MA (should be near enough) and he's got many years experience with M37s (not that the folks here don't) and he's got tons of parts and knowledge. I was just up there today picking up some stuff I couldn't find anywhere else. (Passenger seat latch, military seal puller, etc) It might make more sense to do a swap with a decent take-out engine but you know the risks associated with that. Anyway, Bob doesn't do internet so you'll have to phone him: five-oh-eight- 384-seven-six-nine-eight.

 

[shootist]

Funny you mentioned Bob
Many a part comes from him on my truck.
I was gonna stop by and see him this week some time
was really hoping to show him the truck at the show
I was headed to but.... we all no what happened that day......

 

[shootist]

Ok I decided to pull it and rebuild it.
Ill keep you all updated with what I find.

anyone feel like running me over?

 

[WarrenD]

I know the feeling......sorry man!

While you are in there, you might want to check the cooling tube behind the water pump. They are known for rotting out and then bad things can happen.

 

[armytruck63]

You can break the cylinder glaze by using the old piston and some valve grind compound (assuming the bad wrist pin has not caused cylinder scoring.)

Now that is a useful tip - thanks OF!

 

[armytruck63]

I would also go the full rebuild route, based on the amount of crap that was circulating in the oil. Good luck on the job.

 

[Oldfart]

I know the feeling......sorry man!

While you are in there, you might want to check the cooling tube behind the water pump. They are known for rotting out and then bad things can happen.

This is a good point as a rotted out cooling tube will cause all sorts of heat/cooling problems and is frequently over looked by most engine shops.

 

[shootist]

yes thanks for the reminder Warren and OF
I almost forgot about the cooling tubes
let me ask this: if there is an issue with them- pull em out
and forget em or try to find new ones and replace.

also I read somewhere in a TM how to pull the engine with out removing the fenders- any thoughts? Or a TM number?
I really dont want to get into pulling the heater its on the fender
-it was not fun to install-

 

[WarrenD]

You should be able to yank the engine without taking off the fenders but you might have to take off the hood or prop it way up. Radiator should probably come out, then pull the engine forward and up. Be very careful with the exhaust manifold and when you re-assemble, use the correct fasteners and proper torque. My former owner didn't and the manifold cracked when it couldn't expand and contract. He then snapped the stud and the truck sat for 8 years before being rescued by my seller.
Call John Bizal at Midwest Military about the cooling tube. I know he doesn't have any (as of last week) and he said quality control had been an issue so he was setting up a machine to make them himself. Not sure of a timeline, but he might be in production by the time you need one. Don't know if Bob Stahl might have a tube in stock, never hurts to ask. I think I'd wait until I got in there, you might be ok and not need one.

 

[Oldfart]

Shootist,
The cooling tube is key to water circulating properly in the engine. Without it, you get hot spots and cold spots (rear cylinders tend to run hot and yet, it is difficult to get hot water to a water style heater.) ~~ I prefer to pull the whole front clip to get to the engine. The radiator, grill and all comes off with the fenders and can be set aside with two or three persons to help lift (I have done it with a hoist by myself.) But, the beauty of M37's is that you can do it several ways depending on what your needs/wants are. If the brackets are still there for bolting the radiator to the block, the whole power unit (radiator, engine, transmission) can be removed as an assembly. Or, you can pull the grill and radiator alone to access the engine. As I said, I prefer to pull the front clip and the floor board over the transmission which gives all sorts of room to pull the rear motor mounts and it makes it easy to get all the plumbing detached and re-attached. ~~~ Check out a couple of M43 restorations by Zout and Ghostdriver on SS to see what front clip off and radiator/grill removed look like. Two different ways to get the job done that were dictated by different needs of the rebuilders.

http://www.steelsoldiers.com/m37/67402-coming-attraction-project-6-m43-build.html

http://www.steelsoldiers.com/m37/68381-m43-resurrection.html
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