My 1952 Dodge M37 re-building process

[Cal_Gary]

Purchase a rebuilt ETW1 from John at Midwest-I did, 12 years ago, and it still runs flawlessly.
Gary

[Argie1978]

Hey, Gary...you're back, mate.
Well, I have news,....I've exchange a few mails with John and he will rebuild an ETW-1 for me.
I have reached out to 10 different people around the globe for a rebuilt carburetor.
7 replied
4 declared out-of-stock
2 offered only the core
1 offered a complete rebuilt (Midwest).

As this takes a few weeks I've set a plan to going forward with the remaining stuff at the shop, like brake drums, lights, etc.

[Cal_Gary]

We don't fix these trucks without each other's help; hence my reply my Friend!
Thanks,
Gary

[Argie1978]

Sh..t happens.

Tears like rain.jpg (28.45 KiB) Viewed 35385 times

[Cal_Gary]

Oh that sucks! Sorry!
Gary

[ashyers]

Argie1978,
I just had a radiator re-cored. It was $$$! The price of cores has become nothing short of spectacular. Grant, the radiator guy, essentially cut off the folded seams and ordered a core to fit to the flanges that were remaining. It's not "original" but he felt it would be just as durable and more repairable if there were issues down the road. In addition the core had a different fin/tube matrix that should be much more efficient that the original design.

The radiator I had that failed peeled the entire front seam open when it went with a big bang. That was likely encouraged by a head gasket failure helping it along . If you decide fix the header tank, check that seam carefully!

Were you running a 4 psi cap?

Andy

[Argie1978]

Hi Andy,
I cannot tell for sure if the radiator is original, mainly because the Spanish army used to swap a lot of things at the depot. I don't have clear pictures where an original radiator is shown. And the cap, as far as I now, was a 7-8 PSI cap.
I am a bit scared of what happened. After talking with the shop we agreed the 3rd party that restored the rad didn't tested it at high pressure. But to be fair, the pressure was too high. The return hose was very swollen the few minutes the engine ran. I'm crossing my fingers not to have a head gasket failure. This shouldn't be, I mean the engine just got from the machine shop a few months ago and now we are back into running it.
I know it can happen but this would mean more time at full stop. Yes, better to prevent that cry after.
Now the radiator has been taken to another shop that will remove the head while maintaining the core. All this for 275€. It's the cheap option. Indeed, servicing this piece is really expensive!

[PoW]

The original M37 radiator has two, deep cores. This is the same thickness as a regular 4-core radiator.

The top tank overhangs the core in front, by some 3 inches. The tank takes a mil-standard cap, 4 to 7 lb rating.

Both outlets are cast iron, riveted then soldered in.

I hope this helps.

Too bad you're so far away, I have several good ones and would give one to you.

Dennis

[Argie1978]

Too bad you're so far away, I have several good ones and would give one to you.

Let's see what happens, Dennis.
And I would keep those rads because for the moment this restoration is going uphill.

[Argie1978]

1st compression test (a few days before the rad blowup)...


The new pump installed.


Still awaiting for the carb from Midwest, so the project is in hiatus in terms of the engine. Yes, the radiator is finished and the specialized shop will send it back maybe tomorrow or on Thursday.
Still finishing the electric part and some body parts. Will put pics when possible.

[John Mc]

Unless I messed up my Bar to PSI conversion, those are some real problem compression readings. Have you looked in to it further, or are you planning an engine rebuild?

I was under the impression that the radiator cap for these engines was supposed to be rated at 4 PSI

[Argie1978]

Never said it was right, John. I am putting all the info for you guys to see.
Indeed it's wrong....., the engine sounds great tho.
I cannot re-test until getting the radiator back. And this is the engine AFTER rebuilding it. We're losing it.
NOTE: we just ran the engine three times, no more than 1 min each.

[John Mc]

I was not criticizing your post... more commiserating. Sorry if I gave the wrong impression.

If you have only run it for a few minutes, I suppose it's possible the rings have just not seated yet? I'm no engine guru, and never checked mine when I first got it back from the rebuilder. (I did not check mine until I had about 500 miles on it.)

[Argie1978]

Never thought in a bad way about your comment. No worries.
We just ran it in very short time spans to check for the starter, do a simple compression test, check for the water pump, etc. Yeah, the idea is, once the "new radiator" is installed, to verify properly for the water pressure (possible head gastes issue) and check for how it behaves while straightening out. Note that we don't have the carb yet, so it's a long way to have everything in place to get real numbers.

[PoW]

Well, the M37 engine was designed to run OK on 68 octane gas.

Low compression was necessary so as to not knock, even on rotgut gas.

Most of us mill the head enough to get it up to maybe 8:1 or so, with modern gas. Sure will have more pep...