55 M37 hard starting

dodger · Post by **dodger** » Thu May 01, 2008 1:18 pm

Hi everyone I'm just new here and found this site while trying to look up info for the M-37 I just bought. I'm having some troubles with it starting hard and was hoping to maybe get a few pointers on it.

The guy I bought it from said he put a new carb on, I don't know if it was new to him or ? Basically once you get it going it runs pretty decent, the guy I bought it from said it always started well but it didn't when I went to pick it up so... You have to crank it for about 3 minutes before it will start firing and then finally it will go. It starts hard cold or hot. I've changed the fuel filter and thats about it. Where it came from the alt. was 600ft and I'm at 2500ft. if that makes a difference. Any ideas? Thanks in advance for the help.

refit1701 · Post by **refit1701** » Thu May 01, 2008 2:42 pm

I'm a fairly new owner too and I can tell you that mine likes to run with the choke at about 30% closed. Even when she's running, opening it up all the way seems to starve the engine.

I'm sure there's an idle adjustment or something that's going on but once I got the choke set, she starts pretty easy. This is with a rebuilt carb.

I'm sure the others with more experience will chime in shortly.

Oh, and Welcome!

MSeriesRebuild · Post by **MSeriesRebuild** » Thu May 01, 2008 3:16 pm

refit1701 wrote:I'm a fairly new owner too and I can tell you that mine likes to run with the choke at about 30% closed. Even when she's running, opening it up all the way seems to starve the engine.

I'm sure there's an idle adjustment or something that's going on but once I got the choke set, she starts pretty easy. This is with a rebuilt carb.

I'm sure the others with more experience will chime in shortly.

Oh, and Welcome!

If you have to leave the choke out any at all, you likely have 1 of 2 things going on. A vacuum leak or a seriously lean fuel mixture most likely related to a carb issue.

MSeriesRebuild · Post by **MSeriesRebuild** » Thu May 01, 2008 3:19 pm

dodger wrote:Hi everyone I'm just new here and found this site while trying to look up info for the M-37 I just bought. I'm having some troubles with it starting hard and was hoping to maybe get a few pointers on it.

The guy I bought it from said he put a new carb on, I don't know if it was new to him or ? Basically once you get it going it runs pretty decent, the guy I bought it from said it always started well but it didn't when I went to pick it up so... You have to crank it for about 3 minutes before it will start firing and then finally it will go. It starts hard cold or hot. I've changed the fuel filter and thats about it. Where it came from the alt. was 600ft and I'm at 2500ft. if that makes a difference. Any ideas? Thanks in advance for the help.

My first thought is to perform a compression test on the engine. What you have described sounds very much like it may be caused by low compression issues.

Lifer · Post by **Lifer** » Thu May 01, 2008 4:10 pm

Of course, it might just be a carb adjustment issue. There's a big difference between 600' and 2500' altitude. You may be running a bit on the rich side, considering the elevation where you are.

MSeriesRebuild · Post by **MSeriesRebuild** » Fri May 02, 2008 5:10 am

My reply was based on the original message, always cranked great for the seller, however it didn't crank well when the buyer went to pick it up. It was still at 600' altitude at that time. I'm never optomistic of sellers stories of how good they are, I could write a book about "how good they are stories" from sellers; I could also write one called "the truth about heart broken buyers." Just saying what I've experienced. The compression test done correctly will shed the light in the right place & hey, if the test result is good, you can breath a big sigh of relief. There may be carb issues here also, but I also get the feeling there is a much larger picture in the background, just a gut feeling.

dodger · Post by **dodger** » Fri May 02, 2008 5:36 am

Ok I'll do a compression test this weekend, what are the parameters for these engines?

MSeriesRebuild · Post by **MSeriesRebuild** » Fri May 02, 2008 8:18 am

dodger wrote:Ok I'll do a compression test this weekend, what are the parameters for these engines?

The very best readings would be in the 120-130 PSI range. This is what you would expect in a newly rebuilt engine with 1,000 or so miles to break it in. The 110-120 range is good, certainly not in need of a rebuild, but showing normal wear. 105 is getting on the lower end of acceptable in a good engine while 100 is border line. 90 PSI or lower will likely be running irratic with a high likelyhood of 1 or more cylinders skipping. Ideally, readings from 1 cylinder to the other should vary no more than 5 PSI. Low readings can come from ring/cylinder wall wear or valve train issues. Post the result of your test here, will be glad to help you from there.

Lifer · Post by **Lifer** » Fri May 02, 2008 10:38 am

You're right on the money about the "stories," Charles! Every seller has a vehicle that "starts easy and runs like a Swiss watch." Even the ones that "ran when parked." When the buyer arrieves to pick it up, he often has a totally different concept of "starts easy and runs like a Swiss watch." That's when the real dickering begins.

("Pssst! Wanna buy a bridge?")

dodger · Post by **dodger** » Fri May 02, 2008 10:53 am

Ok I'll check it when I get back home again, I agree with what you say about sellers saying it runs like a swiss watch but doesn't this time for some reason. Thats why I worded it the way I did earlier just so everyone took it with a grain of salt. I always thought guys that did that were full of BS but a couple weeks ago I was selling a motorbike and when the guy went to test drive it, the clutch wouldn't work. It never did it before and never did it again after that either.

anthony manzella · Post by **anthony manzella** » Sat May 03, 2008 5:27 am

[ JUST SOMETHING OFF THE WALL ] check to see if the plug wires are in the right order when I pick mine up down in TX 2&3 where switched it ran like poop! hard to start and run , Iam no way like the other two guys that have tons of expertice on these trucks just got lucky with mine after I pick up some on line info good luck with yours . [ you all come back now here ! ]

dodger · Post by **dodger** » Sun May 04, 2008 12:51 pm

Well here's the results and they aren't good. From front to back ( I don't know which cylinder is which so the numbers go from the rad to the firewall) 60-60-60-60-0-40. So now the question is, how much for a rebuild kit? (rings,bearing and gaskets) where do I find them? I'm Canadian so it would be good to find a source here but I can also get them shipped to a friends house in ND. How much are the diesel conversion kits?

Thanks again everyone,
Dodger

gwalker · Post by **gwalker** » Sun May 04, 2008 2:51 pm

You may just have a blown head gasket between the last cylinders. Take the head off and see, you may not need to rebuild the engine.

Lifer · Post by **Lifer** » Sun May 04, 2008 3:24 pm

dodger wrote: ( I don't know which cylinder is which so the numbers go from the rad to the firewall) 60-60-60-60-0-40.

The #1 cylinder is always the one closest to the radiator, so you have them listed in the correct order from 1 through 6. Your test results are way less than good, I'm afraid. I don't think the problem is simply a blown head gasket, though. They usually let go between cylinders, which results in lost compression on both affected cylinders. It's possible that simply replacing the head gasket could get you up and running, but the other compression readings indicate that there's more to the issue. At a minimum, I'd suspect that the "zero" reading on cylinder #5 is due to the exhaust valve being stuck open. To be perfectly honest, I think you're looking at a rebuild in the very near future.

DJ · Post by DJ » Sun May 04, 2008 7:21 pm

Before I went any further I would check compression with another gauge. He stated it ran decent after it was started,60 lbs wouldn't run decent. One other thing when starting the choke must be used properly,or you can have starting problems. If you're new to the world of flatheads you'll need tto learn how to start them properly.

DJ

55 M37 hard starting

55 M37 hard starting

Re: 55 M37 hard starting

HARD STARTING