Operating Temp Chrysler 1972 203HD 20hp Question

[3rdMarDiv]

Working on a Chrysler 203HD 20hp that is running very rough. Won't operate at WOT. Boggs down and quits. Runs pretty well at low speed with muffs on...:grumpy:

It's gotten cold here in Michigan and since this motor has no thermostat, could the cold water be keeping it from getting to operating temp...?

I used a lazar temp reader with the muffs on and the upper cylinder reads 120 to 130 fine, but the lower cylinder doesn't break 100 degrees. I reciently installed a new gasket, checked head to less than 4 thousands space anywhere on the head, etc. Torqued to 190 in lbs...

The outside temp is in the 40's here and I'm sure the hose ater is very cold. Could the water be warming up as it passes the lower cylinder enough to allow the upper cylinder to heat up properly...

When I tried to run it in lake erie it really fouled out and I had to get back using my trolling motor...

Just trying to eliminate another cause of the problem...Thanks for any assistance

 

[Frank Acampora]

Re: Operating Temp Chrysler 1972 203HD 20hp Question

I doubt if water temperature is the problem. Water flow is or should be similar to the larger engines: It flows first through the exhaust chest. It then exits to the top of the block and runs down one side of both cylinders and back up the other. It then passes through the thermostat, down the head, and exits into the midleg.

Check fuel supply and ignition.

 

[3rdMarDiv]

Re: Operating Temp Chrysler 1972 203HD 20hp Question

I doubt if water temperature is the problem. Water flow is or should be similar to the larger engines: It flows first through the exhaust chest. It then exits to the top of the block and runs down one side of both cylinders and back up the other. It then passes through the thermostat, down the head, and exits into the midleg.

Check fuel supply and ignition.

Thanks for the input. I also did not think that would be the problem, how could you fish in the winter...LOL

I will check next the ignition coils and timming. The points are good and and I gapped them at .020. One coil has some seperation between the layers of stacked metal layers.

Again though, this model motor has no thermostat...Thing they started putting them in like 1975 or 76...?