M37 coil problems.

Rail man · Post by **Rail man** » Tue May 06, 2008 6:08 pm

Hello everyone l'm a new member and this is my first post. i'm working on a 1953 m37 that likes to eat ignition coils. I started with the original coil every thing seamed ok for about 250 miles. Then it started to sputer then stall after cooling some it would start and drive but not to far.Ultimatly it would not start anymore. After checking for spark l realized the coil was very weak,so l purcased an imported one that had made in china on it.Well it started the engine,and it ran for about 3 min. Since NOS is not available l bought a new star import. This one put about15 miles on it.DEAD again. I just can't understand what could be the problem, as the vent lines and electical system is new. If anyone has an idea l sure can use the help.

knattrass · Post by **knattrass** » Wed May 07, 2008 3:38 am

Cooling check?

We just re-wired as well. We bought an electronic ign kit from Charles which dropped right in and eliminated points/cond. Then we removed the RF filter and ran the positive wire from the coil, down thru the connector hole, and connected to the harness lead. We filled the oil resv on the side, and added a few drops of oil to the wick underneath the rotor. We replaced the dist cap seal, the connector seal, and the dist/engine block seal. When we installed the 2 vent lines that run over to the intake elbow, we found that the 90 degree flared fittings did not have the little pitot tube vents to force cooling air in/out of the dist. We cut a 1 inch piece of 1/8 copper tube, bent it 90 degrees and soldered it to the lead fitting so that when its installed, the tube points head into the air flow (pos). Then we did the same for the rearward fitting and installed it pointing downstream in the airflow (neg). We also used new standard length steel brake lines (36 inch i think) and bent new tubes for all 4 vents because one was crushed at a bend and the others rusty.

MSeriesRebuild · Post by **MSeriesRebuild** » Wed May 07, 2008 8:26 am

Sounds like the coil is overheating. Keith has likely nailed the problem with an issue of some sort with vent tubes/fittings. Air must be forced through the distributor to keep this problem from happening.

HingsingM37 · Post by **HingsingM37** » Wed May 07, 2008 9:01 am

What is the proper position for the cooling fitting tubes in the air horn? Right now I have the 45 degree tube on the outboard fitting pointed straight down. I have the short pitot tube on the inboard side with the bevel pointed down. I will be buttoning up my air cleaner and I want to make sure they are postioned correctly?
Thanks!

peter e mark · Post by **peter e mark** » Wed May 07, 2008 10:06 am

Hello David, And I think Charles pointed to the position of the "in" and "out" tube, as having different aim points in the air horn so as to establish actual air flow thru the distributor. I recall seeing pictures of these fittings and thier respective position in the service manual .( is it TM 880 ? ) It's the one that John Bizal sells. Peter

Rail man · Post by **Rail man** » Wed May 07, 2008 12:32 pm

knattrass I did make sure the tube was pointing upwind,but the other one was not bent 90,it was cut on an angle. The distributor cap gasket is new as is the distibutor to block gasket.Do'es it matter witch line is the in on the distibutor?

Lifer · Post by **Lifer** » Wed May 07, 2008 1:08 pm

Yes. The one that points "into the wind" should be the air inlet for the coil. That way you get a little bit of "ram air" effect that forces air through it.

knattrass · Post by **knattrass** » Thu May 08, 2008 3:32 am

We found the one fitting that has a straight tube 1 1/4" long sliced at a long angle plugged into the dist (go figure?) and was FUBAR'd. Holding the fitting in its installed position, we noticed that the slice was facing upwind. This would have indicated that it was cut to grab the airflow (pos). If your tube is soldered to the fitting facing the wind, then it would install in the hole towards the elbow opening. We had to bend a small tube to simulate that effect. If your tube faces downwind, then it is the vacuum, and would install in the downstream position.

Rail man · Post by **Rail man** » Thu May 08, 2008 12:24 pm

I understand how to make the air flow in the dist.. Does it matter witch side of the dist. it enters? Something l rememberd when the truck stoped l emedietly openend the hood and put my hand on the dist.I was able to keep it there for as long as l wanted.How hot is too hot? The dist. was the coolest thing uder the hood.

MSeriesRebuild · Post by **MSeriesRebuild** » Thu May 08, 2008 1:18 pm

Rail man wrote:I understand how to make the air flow in the dist.. Does it matter witch side of the dist. it enters? Something l rememberd when the truck stoped l emedietly openend the hood and put my hand on the dist.I was able to keep it there for as long as l wanted.How hot is too hot? The dist. was the coolest thing uder the hood.

Makes no difference about direction of air flow. Doesn't take a lot of heat to bring a coil down, it's tight quarters inside the housing, not much room for air to circulate around the coil, thus ventilation has to be working top notch.

Rail man · Post by **Rail man** » Thu May 08, 2008 3:10 pm

What about coating the coil with grease? I've heard that it promotes heat transfer.Seems like it may interfear with air flow.

MSeriesRebuild · Post by **MSeriesRebuild** » Thu May 08, 2008 5:21 pm

Rail man wrote:What about coating the coil with grease? I've heard that it promotes heat transfer.Seems like it may interfear with air flow.

The coil should be clean & dry.

Lifer · Post by **Lifer** » Thu May 08, 2008 7:13 pm

Rail man wrote:What about coating the coil with grease? I've heard that it promotes heat transfer.Seems like it may interfear with air flow.

Like Charles said...it should be clean and dry. I don't know who you've been listening to regarding vehicle maintenanvce, but you'll be far better off listening to the guys on this forum. We (usually) know what we're talking about!

Oh, yeah. Before I forget again...welcome to the club!

Rail man · Post by **Rail man** » Sun May 11, 2008 1:29 am

I've taken the cooling system apart and found everything in order as it should be.One tube is pointed upwind,the other downwind,all seals are in good order.I put a little compresed air to the vent lines befor reataching them to the elbow.All this was good from the begining,so what else could be causing the coil too go bad. knattras mentioned removing RF filter and runing fromcoil directly to wiring harnes. Is there an advanage to doing this and how do l use the water tight fitting?

knattrass · Post by **knattrass** » Sun May 11, 2008 4:33 am

R/M - by the graces of these guys I learned alot!! So I take no credit for clever or insightful knowledge!!

We overhauled the dist piece by piece and knew from the start that we wanted to switch over to an electronic ignition for reliability and one less variable for setting the engine up. Going that far, it only made sense to remove the RF filter to max out the spark. We sized a ring connector to the pos post on the coil with 18" of wire lead. We pulled the small cannon connector off the dist, pulled the wire thru the dist seal (small hole where the RF pin goes thru), and then straight thru the cannon/s and then terminated the other end with a packard connector. We taped the exposed wire and painted the ends with liquid tape to seal. So you end up with a single solid wire from the coil to the packard. The whole cannon connector is fake and merely provides the various seals to the unit.

M37 coil problems.

M37 coil problems.

Coil problems