Posted: Mon Jun 01, 2009 8:30 am Post subject: M38A1 Overheating!
My A1 overheats (goes past 200 degrees) and boils-over within 10 minutes of idling. I've changed the thermostat - no help. I haven't checked the timing or carb adjustment, but the jeep starts and runs great, so I don't know how it could be a timing or carb issue. Looking in the radiator fill neck, there seems to be a lot of crud in there, so I suspect the radiator is clogged. Does that sound right to you guys? Is there a way to confirm the radiator is clogged before I start taking things apart? The TM states to clean the cooling system per TM 9-2858. What's involved with that? Should I just take the radiator to a shop and have them look at it? The first time the radiator overheated, I wasn't paying attention and the oil pressure dropped to 10 psi. Should I change the oil as a precaution?
Any help with this matter would be greatly appreciated. I'm at a standstill until I can figure this out. Thanks!
The relationship between engine temp, oil temp and oil pressure is a simple physics issue. High temps = low pressure. The only reason to change the oil now is if there is coolant in it and if there is you have bigger problems than just a clogged radiator.
What you describe is in all liklihood a clogged radiator. If you wish to confirm that without special equipment then just remove the lower hose and block the upper hose and add water to the cap and if that water doesn't flow freely out the bottom hose opening it's clogged. Don't fool with it. Just take it to a radiator shop and have them boil it out and if necessary rod it as well.
If water flows freely through the radiator then re-connect the lower hose and disconnect the top hose and fill the radiator untill water comes out the top hose. Then start the engine and keep the radiator filled with the hose. With the thermostat closed there will be an inital slow flow of water but it will be a positive flow. As the thermostat opens this flow will speed up considerably. If no flow you have a clogged block or bad water pump. If the flow never speeds up you have a thermostat stuck closed.
Pull the thermostat and put it in a pot of water but don't let it lay agianst the metal parts of the pot. This usually takes a bit of small wire to wire it up so it dangles in the water. Stick a thermeter in the water the same way. Now heat the water on the stove and observe the temperature when the thermostat starts to open and when it is fully open. If it matches the book spec the thermostat is good and your block is clogged up. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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