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Can anyone help me with my M-37? Had motor and carb. rebuilt did a compression test right after the rebuild only 90psi? give or take 5-6 lbs.in each cyl. tried to start the motor very difficult had to spray gas/starter fluid in the carb.in order for it to start.It would only idle rough for about five minutes then barely run at all.Bogs down or stalls if I try to rev it up. Had new plugs that carbon up after each starting. After the motor cools it seems to run as before, heats up the same thing happens???


Thanks Tomsm37

Could you give us some more information on what specifically was done as part of the engine and carburetor rebuilds?

Was the truck running before the rebuilds? What was the reason(s) for having the rebuilds done?

Agreed, happy to help you diagnose but we need some historical info.
Welcome aboard!
Gary

Thanks for your reply guy's . After I bought the truck got it home I was able to get it started only after day's of trying, using ether/pouring gas down the carb. finely got it to start for a about a half a minute with lots of smoke. Notice some anti freeze in the oil. Did a compression test that showed the psi anywhere form 65 to at most 85lb.also noticed oil in the exhaust pipe this is why I got the motor rebuilt.

The guy that rebuild the motor told me it had a bad piston, he bored block, clean and polish crank, one set of new rings, valve work, timing chain. This is all I can make out in his invoice. I think he may have done something wrong? Shouldn't the compression be a lot higher for a new rebuild? The carb was totally rebuilt twice. The first time was a local independent guy that all he does is carburetors. The other company was Vintage Power Wagons. Could the valves be adjusted wrong? Why do you think when it gets hotter it runs worse?

Thanks, I hope this will help you in pointing me in the right direction If their is any other info that will help you to diagnose the problem let me know.


Tom

Perhaps you could post a scan of the invoice (with your personal and the shop's information blanked out, of course), but from your description, he did not "rebuild" the engine. If he only replaced one set of rings, I'd be looking for a new engine guy. Some of the work doesn't make sense, e.g. "clean and polish crank", but no mention of new bearings?

A truly rebuilt engine - with new rings, pistons, and bored and honed cylinders - sometimes takes a bit of run in to seat the rings to the cylinder walls before the compression numbers come up to spec, but something's not right here.

Did he ever explain to you why you found coolant in the engine oil, and oil in the exhaust pipe?

And oil and antifreeze mixed smacks of a blown head gasket-mine did exactly as you described when it blew: smoke everywhere, antifreeze in the oil, wouldn't continue to run on its own, etc. Your compression numbers are way too low that also suggests a head gasket leak, cracked head or cracked block, or ill-fitting rings.

Vintage Power Wagons is a reputable vendor. If they rebuilt the engine they may be able to provide the history if you can give them the block serial number (located on the left-front top, usually hidden by the generator).

Let us know what you find out!
Thanks,
Gary

pooling gas in the intake manifold will lead to hard starts and fouled plugs. its tough to wash down the cylinders with the way the valves are orientated in a flathead but that's not to say it cant happen. as the motor heats up and increases rpm the pooled gas in the intake works its way into the combustion chamber creating an increasingly rich mixture fouling the plugs and coking up the pistons.

1. verify the fording valve is open.
2. crack open a fitting on the pcv system below the douglas valve.
a. verifies over fueling
b. stops excess gas from entering crank case.
3. remove pipe plug from intake manifold and use a piece of paper as a dip stick to verify that there is no pooling gas in the intake.
4. clean spark plugs and replace
5. remove top of carburetor and verify the float level and the check valve operation. prime carb with the hand lever on the stock fuel pump or cycle electric pump. verify accelerator pump operation.
6. timing should be set to a maximum of 4deg before tdc.
7. with a clean intake and plugs crank the motor and be stingy with the choke. a quick blip in and out is all she should need.

keep in mind the accelerator pump is operated by vacuum. there is no mechanical connection to the accelerator pedal. with the choke fully closed a few seconds of cranking can fill the intake with gas.

Thanks, I spoke to the guy who rebuilt the motor he claims that he bored the block and replaced all cyl. with over size pistons & replace bearings.
He also thinks too much gas is causing the problem.
I tried to attach his invoice but couldn't because the file is to big.

Tom

I spoke to the guy who did the motor rebuilt, he said he bored and replaced the cylinders (over size) and rings, he feels too much gas could be the problem.
I tried to attach his invoice but the file is to big?
I don't see any more oil or inti freeze since the rebuild.


Thanks Tomsm37

Where are you? If local, I'll look at it and figure it out. Btw. I prefer Yingling beer.

what about the tune up parts? new points? set with dwell meter? are you running electric fuel pump? if so is pressure maybe too high flooding carb?

Check yer valve clearances and timing.

PoW

The coolant in oil and low compression on 1 cylinder strongly indicate blown head gasket. He never updated post with answer.