98 bluebird overheating

[Paula Blough]

My bus overheats if the heater isn’t on. With the heater on it runs like it should. Any help would be helpful.

[PorchDog]

For some reason or other-- your radiator is not doing its job.

Did this begin suddenly?

Coolant level?

Check the temperature of the radiator hoses at the inlet and outlet of the radiator and see if coolant is actually flowing through the radiator. It could be stopped up.

Radiator cooling fan may have a clutch that has malfunctioned, but as cold as it is-- looks like it would cool without the fan at this time of the year.

[turf]

just overheating?

replace the thermostat and water pump. on a cummins, thats less than $100 of parts.

if it overheats under load, then maybe the problem is deeper. fan clutch or something.

start with the easy cheap fixes first.

change parts until it works

[magnakansas]

over heats in town, stop and go driving?

Over heats on the highway?

When you say "over heats" Do you mean over 240 degress?

How long from a cold start does it take to overheat?

Does this smell "hot" to you?

Do you have a second method to check the engine coolant temperature?

Have you verified the temperature gauge on the dashboard is correct?

some questions in order to help figuring out what is going on.

william

[Paula Blough]

My Jankmonster blew a coolant hose about a month ago, lost all coolant all over the road. Fixed that, refilled with fresh coolant. Still overheating so I took her to the shop. They said there was air in the system, and did a flush and fill on the coolant. It was fine for about two weeks, then she started to overheat(warning light came on) so I turned the heaters on and she came back down to normal temp. And as long as the heaters are on she stays cool. Runs fine. But turn the heat off and even at an idle, parked she tries to overheat.

[PorchDog]

My guess is you still have some air trapped in the system.

[Jolly Roger bus 223]

could be the engine coolant pump isnt moving fluid but turning the heaters on turns a secondary coolant pump on that gets the coolant moving. ???

[magnakansas]

That’s big.

Water pump failure.

Crack in cylinder head/engine/head gasket failure.

Air in cooling system.

All of the above.

I sure have to wonder at the cause of initial hose failure. Hose was possible result of a undiagnosed problem.

William

[cadillackid]

is this a CAT engine? if so there is a little small water-pump belt that is behind the main serpentine belt.. if that belt gets worn, the water pump wont spin fast enough to keep the engine cool..

[Paula Blough]

Originally Posted by PorchDog

My guess is you still have some air trapped in the system.

Took her back to the shop. She had air trapped in the system. And a bad coolant cap seal.

[o1marc]

Running the heaters only cools it slightly more. If it's normal with the heat on, I suggest it's not "overheating" without them on, even though the guage may show it.

[magnakansas]

happy to hear you got this resolved. Thanks for posting how it was resolved.

cheers

william