Lately my 1987 Raider has been running hot - about 3/4 up the scale. I drained and replaced the cooling, and put in a new thermostat, no change. I used Prestone cooling system flush, but nothing changed. It has never overheated since rebuild.

I really need to get this fixed, but don't want to be out cash - I don't have any, and I'm getting rid of the Raider in the Fall. Will removing the thermostat entirely help? The water pump was replaced early this summer.

Any help greatly appreciated - and anyone interested in buying a Raider with 270,000 miles (rebuilt at 170,000) let me know - I'm thinking pretty low bucks.

Lee

Get the radiator rodded out and check the cooling fan clutch.

If it's running warm at highway speeds, the radiator is the likely culprit. If the issue is only at idle and/or under 45-50 mph, the cooling fan is the suspect.

Frank

New Mitsubishi fan clutch last summer, so I doubt that's it.

Radiator rodded at 170,000 miles - that was about 105,000 miles ago. Could be.

Idle or highway doesn't make any difference (or not much) - the only thing that seems to matter is ambient temperature. If it's in the 60's or lower it runs nice and cool.

I paid $100 for rodding last time, can't do it again right now (and wonder if the radiator would take it), looks for a "band-aid" to get me through.

Any help?

How long ago was the rebuild? A long time I hope- otherwise that means you have a new rebuild with a 100k radiator?! <img src="/forums/images/graemlins/scared.gif" alt="" />

Get it rodded...!

Was the fan clutch an OEM? I have an aftermarket on the 95 that is at least two years old now and fine. I was out of town and thought the 87 needed one, so I got an AM for it and it was crap out of the box.

Check/replace the thermostat. If you're lucky, that might be the only thing wrong.

Frank

The radiator was rodded when the engine was rebuilt, and the fan clutch is OEM (well, I got it at the Dodge Dealer, but it's a Mitsu clutch).

I'll try replacing the thermostat - even though it's new - I know they can be bad, fresh off the shelf.

Lee

Have you tried testing the coolant temp sensor to see if it's reading accurately? Essentially, you remove it and heat up some water on the stove to a certain temperature. Then you immerse the wet part of the sensor and check its resistance. After that, you bring the temp up on the stove, repeat, bring the temp up some more, repeat. It's all detailed out in the FSM. Verify temp with a digital thermometer...they can be gotten for a couple of bucks in the kitchen supplies section at Wal-Mart.

Have you done anything with the fan shrouds recently (assuming your truck had A/C to begin with)?

Have you leaned-out your carb (doing so will increase temp)?

Have you done anything which could have any obstructing effect on the airflow to the front of the fan? Things like new bumper, winch, grill changes.

Do a fan clutch test. Easy to do. Start motor with it completely cold, then with you standing outside the truck, the hood up, and you able to watch the fan, shut the motor off before it warms up at all (in other words, right away). Verify the fan stops spinning immediately. With the engine cold, if it spins longer than the engine does when the engine is shut down, your fan clutch is worn.

Check to see if your oil level or coolant level is rising or reducing. If so, could be a sign of head gasket failure. Check to verify you don't have any coolant leaks (pin-holes, water pump not weeping, coolant sensors not seeping). If no leaks, and if coolant loss is occurring, go through checks for head gasket (sweet smell from exhaust, compression check, fluid visible in cylinders, frothy appearance of oil).

While you flushed it, did you get any chunks of gunky stuff coming out? If so, may want to have it professionally power-flushed. The down side is that doing a power-flush could push a water pump closer to internal failure if it's getting close, but that's not a likely outcome in my experience (then again, might be good to know now rather than later). The upside is that if you have any gunky build-up (which your rad-flush didn't remove and could be clogging somewhere) a power-flush should rid you of it.

While removing the t-stat will allow it to run cooler longer during a given engine running session, that won't prevent an overheat situation if something else is wrong.

Do you still have a cat on the EX? Might be plugged.

Check the head bolt torque. If the gasket is going, one or more may be loose.

Is the radiator a 2 or 3 row core? What do the plugs look like? Any really white ones? Watch the exhaust after a cold start. Any white cloud/mist as it warms up?

Not tested the sender, but I'll give it a shot tomorrow.

Fan shrouds are untouched, haven't used the AC all summer (afraid to turn it on, because of heating).

Checked the fan clutch, it's only a few months old - stopped immediatly when dead cold.

No change in oil level, but coolant drops a little. No smoke from tailpipe, nothing strange about the oil color. The only weird smell is when the defroster is turned on, then you smell antifreeze(but only from the drivers side vents) - it will fog the windshield in cool weather! No coolant leaking on the ground. I think this may be the heater core leaking???? Been doing it for a couple of years. No smell unless the heater is on "HOT".

When I flushed it all came out good - I use distilled water and Prestone (in correct proportion) - nothing strange there.

Water pump was replaced early this year, so I (hope) it's not going bad.

Thanks for the help - any more suggestions?