712 stull running hot

[andy]

Ok, I've used air to blow the dirt etc out of the oil cooler, I even went and bought a pressure washer and used it on the oil cooler from the top side and water was coming through the fins.

I'm now thinking maybe it is the thermostadt. SAV has them.

Here's the question? From what I can see in the manual and actually looking at the thermostadt it looks like it is just simply an unbolt and replace job? Is that correct, has anyone ever had to do this? Any knowledge or insight would be greatly appreciated.

Any other things that could be causing it to run hot? I've flushed and changed the oil and filter twice. Did the flush in case maybe the thermostadt was clogged. There was no change.

Thanks, Andy

[Jim LaGuardia]

What do you consider hot?
These trucks run around 180-230 deg f on the highway in hot weather.
Are you sure you have the proper sending unit for your temp guage?
Thermostat replacement takes a few minutes. 2 nuts and pull it out.
Lube the new O ring for the replacement, insert into bore and secure fasteners.

[andy]

Jim, I consider anything above 240 on the guage as hot. Which is another issue, how do I know the guage works and I have no idea (yet) how or where it is wired in or which sending unit it has. It came with the truck.

The thing is, for 2 years, summer or winter the guage would set at about 150-160. That was the normal. Now all of a sudden it is at least 220 and I've had it run all the way up past 260 going towards 300.

Used the air hose about a week ago to blow out the cooler again. Let the truck run at idle and the guage after 20 minutes sat at 220. Got the pressure washer and washed it and took the truck for a test run and after about 4 to 5 miles she was back up to around 260. It normally took about a 6 mile run to get it to 150.

If I'm not mistaken the oil pressure switch (looks almost like one of the selinoids on the carbs) is also in the housing that holds the thermostadt. The wire to it was real loose and grimy, but the light on the dash turns off and on at the appropriate times.

There is no oil seepage at any of the connections from oil filter to cooler.

[Erik712m]

Before you order one. Why not just run it with out a thermostat installed. If it still runs hot it's not your problem.

[andy]

Erik, not sure that might not spill oil. From the diagrams/drawings it looks to me like the thermostadt raises or lowers just to direct the flow of oil either to the oil cooler or to bypass it. Not sure what would happen if there was a hole in the assembly and the oil was flowing throug the motor.

I'm tempted to take the thermostadt out of the 710 and try it, but I worry about the o-ring. I can't afford to have both trucks messed up. Too much feeding to do. Bow season opens in two weeks.

Andy

[Jim LaGuardia]

The thermostat must be in place to run the engine.
I would use an I.R. temp gun on the pan. If you can post a pic of the guage I may be able to list a sender number for you.

[andy]

Thanks Jim, I'll try to get a pic. I know it is a VDO guage. I'm obligated to repair a feeder for a customer tomorrow and I'm not sure how long that will take.

I don't have an IR gun, but if I can find someone with one should I just read the pan or would there be value in reading the pan vs what is going from the filter to the thermostat? I'm assuming by pan you mean the oil pan on the bottom of the engine.

(BTW, the pan on my 710 just had a rust through that caused a leak. Fritz, the guy in Victoria managed to get it welded.)

It's also gratifying to know my interpretation of the drawing on how the thermostat works was correct.

[andy]

I replaced the thermostat on the 712. Temps still unbelievably high.

Today I was able to borrow an IR gun and the temps were: 712 first and 710 second. All temps are F

Oil cooler: 712- 96.7; 710 - 98-100

Thermostat: 712- 137; 710- 160-161

Oil filter: 712- 166; 710- 166

I'm inclined to believe it is the sending unit, still no pic of the guage. It's made by VDO and runs from Zero to 300 degrees.

Does anyone have any other ideas about anything else I need to check before I put this truck back to work?

Thanks,

Andy