Something to check

[Roger Friedrich]

A problem I was having was rear main oil leak and trouble with the engine running correctly.
I tried to drive my M-37 in a university homecoming parade but it wasn't to be. When I got the M home I started tearing it down to see what the problem. I found in the tear down it had jumped time and other problems.
Now in the process of rebuilding the engine and checking things I found the pvc tube going into the intake manifold was clogged with carbon. I used a drill bit to clean it out and hope this corrects some of my problem. The reason is was a problem is the engine is set up to keep water out when you are fording. There is no way the crankcase has to vent causing the pressure to be pushed out the main seals


Roger

 

[GUNNY 155]

If you have all the original piping, valves and lines in place and the fording cable is pulled out you could get pressure building up in the crankcase and force oil out of the rear main seal as well as other places. I see you also were dealing with a blocked PVC system which would give similar results. Most M37's had the fording hardware removed from the engines and were converted to a straight PVC system so by cleaning the port to supply proper vacuum you should be good. I am interested about the engine jumping time. With steel gears and chain to me it would seem that this would take some extreme wear. I use to see that condition on a lot of cars in the 60's with aluminum / nylon composite cam gears but not with steel sets. Pontiac 389 engines were almost guaranteed to have this failure at around 50K miles.

 

[Roger Friedrich]

Gunny

I was surprised to see the timing chain slack as it was. This is the second overhaul the engine has had. Several things have been done like the cylinders have been bored to .040 over and the crank has been turned. I guess they were like me when they saw the price of the timing chain and gears they didn't replace them. I've started to assembling the engine but have ran into some other problems that I need to fix before being ready to put it back into the truck.

I'm like you I've changed several timing chains and gears when they put that nylon coating on then gears.

I have two M-37 currently the second has a locked up motor but is good for referring it when things aren't going together right on the first M

 

[GUNNY 155]

Hope all goes well with your project. When I did the machine work on mine I took it to a local guy who has been in business for 30 years building classic car and racing engines. One thing I had him do was based on a number of articles and threads I read on the SS blog. It appears that these engines are very prone to beating them selves to death because of very poor balance and poor clearances in the big and small ends of the rods. So I had every thing balanced including the flywheel. I also had the rod ends brought to proper spec as far as size and bearing clearance. The main bearing bores were checked for proper size and alignment also. It was a little pricey but I think it will be worth it in the long run. The engine runs very smooth and is as quiet as a swiss watch.

 

[TGP (IL)]

The clogged up PCV pipe is not uncommon.
It's a good idea to check.
Had the same problem on my WDX blowing oil.
After a lot of thought on the leaks I started looking at the PCV system
And come across the pipe.
Pipe was plugged solid. Used the drill method
Amazingly the engine dried up.
And I was about ready to start tearing it down for seals.
Tom