My overheating problems may be solved!

[belfert]

It appears a new radiator cap and new thermostats may have fixed my overheating problems at last.  My water temps were up to 170 degrees by the time I backed out of the driveway and drove the three blocks to the interstate.  I used to have to drive a good five or ten miles to get up to 170 degrees.  I think one or both thermostats were stuck partially open.  Once I was up to temp I was running around 195 degrees instead of 200 degrees on the flats.

I drove up one of the steepest grades I know of here in the Minneapolis area at full throttle and was happy to see the temps only went up three to five degrees.  I'm sure the engine was lugging and I was suprised the B500 did not downshift.  I'm not 100% convinced yet until I can climb a 5% grade for five miles without overheating.

The bad news is I am still leaking coolant from rear side of the engine somewhere around the water pump.  The Detroit dealer said it was not the water pump, but rather the radiator cap.  I'll have to look at it some more.

I forgot to used my infrared temp gun to see if the temps were even across the radiator.

[Barn Owl]

Nice to have the monkey off your back I'm sure. I guess if it's an overheating problem it is a 600lb gorilla that's gone!

[H3Jim]

Thats' great!  I know that's been bugging you for a long time.  Nice to see its not a big expense either.

[belfert]

Just another note.  The radiator cap was replaced, but it appears the water pump could still be bad.

I've not seen any coolant dripping on the ground since I got back from a 60 or 70 mile trip three hours ago, but there was a small puddle from being parked for a day and a half.

[tekebird]

Question:

Prior to cap and Tstats:  Bus would not get up to op temp for miles but would overheat under load/grade
After cap and tstats: bus heats up before leaving the driveway but doesn't overheat

[belfert]

Question:

Prior to cap and Tstats:  Bus would not get up to op temp for miles but would overheat under load/grade
After cap and tstats: bus heats up before leaving the driveway but doesn't overheat

Correct.  I suspect one or both thermostats were stuck partially open before.  It did take me a bit to back out of the driveway since I have trees next to the driveway and the driveway is only 10 feet wide.  The bus was not fully up to temp at the end of the driveway this time, but in the past the needle wouldn't have moved when I got to end of the driveway.

[Dallas]

Just another note.  The radiator cap was replaced, but it appears the water pump could still be bad.

I've not seen any coolant dripping on the ground since I got back from a 60 or 70 mile trip three hours ago, but there was a small puddle from being parked for a day and a half.

Brian,

What you describe sounds like a cold water coolant leak.

These are often caused by poor or improperly torqued hose clamps, or, loose or improperly tightened fittings.
Especially if you are using green stripe or silicone or nitrile hoses.

We use to have these problems on our trucks all the time. The easy fix is to go down to Napa and buy the best stainless steel clamps you can get and replace all of the clamps on the cooling system.

You may also want to remove the screwed in fittings and replace the sealant on them, using something like "Gasoila" thread sealant which is good for sealing up to 10K psi @ 600° for liquid.

Good luck.

Dallas