[jamescurtis]

Back to my newly acquired 1989 B250 again. I find that when I'm going up a long hill, even at city speeds, the temperature gauge starts to creep up.

Other than hill climbing it seems to stay pretty steady, even at highway speeds.

When I get to the top and can coast along it goes back to normal.

This one is new to me so I'm looking for a list of most likely culprits.

Could even be a sensitive temperature gauge I suppose.

I did a flush and fill of coolant a couple of days back and I ran and flushed a non-acidic prestone cleaning solution to take out any sludge it could.

I leave tomorrow night to drive across the continent to California and at the moment I figure some of the mountain passes might take a few hours to cross if I have to stop several times to keep the temperature down.

The fan runs and the water pump runs quietly.

I'm thinking of picking up a water pump tomorrow if I can get one just in case it overheats and I can't find a mechanic on the weekend. Unless the bolts are seized I might be able to swap it out in a truck stop parking lot.

Would running the van in a lower gear up a mountain pass force the pump to run faster and keep it cool? It just seems to heat up when it's put under pressure going up a hill.

Any experience with this problem?

Thanks.

 

[dana44]

Aaaah, the creeping temp gauge and admittance to changing the fluid recently. This sign is a real case of an air bubble in the engine side of the system. Your overflow may be filled properly but there is enough air in the engine side that it isn't able to expand the fluid when warm enough to push the air out and pull fluid back in its place. Try parking on an upper angle when cold, pop the cap, see what the water level shows. If low, fill more and try squeezing and pushing the upper radiator hose so more fluid goes in, cap it when the fluid is full to the top of the cap edge. If this is not the case, which I believe it is, then the radiator cap itself isn't holding pressure properly and allows the temp to go up, hills because you are on the gas more, thus cylinder temp rises.

 

[valiant67]

I'd suspect the radiator. Even the best flush doesn't really clean them out as well as you'd hope.

 

[Doug D]

I'd suspect the radiator. Even the best flush doesn't really clean them out as well as you'd hope.

+1! The scaling isn't always removed even with a good flush. There's probably partial blockage in one or more tubes. It does sound as though the radiator is losing its ability to dissipate heat sufficiently.

I had a 92 Acclaim that started to run hotter than normal at hwy speeds - gauge was at the 3/4 mark and in the normal range (1/3 - 1/2) at low speeds. Replacing the radiator solved the issue.

 

[jamescurtis]

Thanks for the responses. I think you're right about the rad. Given the age it stands to reason. The overflow tank had a layer of black in the bottom and took a lot of cleaning to get it "clean".

The other thing it was doing was running at a good temperature around town and then if I stopped for five minutes and then started it up again the temperature gauge would initially be really high and come back down quickly once the engine ran.

This morning I pulled off the heater return hose because it's the highest point and it was flowing well there.

Then I ran it until it was completely warmed up with the radiator cap off. Something I didn't do the first time. Ignorance isn't always bliss.

This led to bubbling bit by bit over about 5 minutes or so and I had to top up with less than a cup of coolant. At one point it was down below the lip of the radiator cap area. It finally stopped so I capped it and turned the engine off. I haven't checked it again since it cooled down to see how much I lost but it definitely overflowed some.

I restarted the engine after 5 minutes and the temperature gauge didn't go up high like it was before.

I'm not assuming this will solve the overheating problem but every little bit helps I suppose.

thanks again for the advice. I'll let you know if I have to install a radiator somewhere in the desert on the I-80

 

[jamescurtis]

Just went back out and started it up cold again. The fluid was full to the cap but once the thermostat opened I got more burps coming out. Not as much as last time though.

Maybe she's just a gassy old girl. Fingers crossed this will help a bit.

 

[jamescurtis]

The 2600 mile drive to California is done.

The only really tough parts were going through the desert when it was over 100 F. There are several hills heading west from Salt Lake City into the Great Basin and the engine got very hot on each of these. Slowing down to a crawl didn't really help. In the end the best way to cope with things was to drop down to about 40 mph and use the cabin heater with the blower on full. The temperature crept up to one line above halfway and stayed there until I crested the hill. Then it took several minutes of downhill before I could turn off the heat. I was never able to go above 55 mph without the engine getting hot.

Around 9 pm I drove over the Donner Pass into California and didn't have any problems with overheating. It seems to be very dependent on ambient temperature.

Since there's nowhere around here I can work on the van, I've made an appointment to have the rad and water pump changed. Plus the belts because one is quite loose and I'm not sure of the age of the others. I still have to drive back across the country in August and I don't want a repeat of my experience from last week.

 

[jamescurtis]

The van now has a new rad, which was described as looking pretty worn out, with a lot of compromised fins. The old rad was a single row rad but it was replaced with a double row one that will hopefully cool things much better. Since most of my drives are planned in summer heat, it should be a welcome improvement.

It also had a couple of loose belts and I didn't know what the water pump was like so I had all the belts and the pump changed. I tried to loosen one of the belt bolts back in June and worried that if I put any more force into it I risked breaking it. Since I don't have any heat to crack the bolts, I bit the bullet and had the work done in the shop.

They also replaced the cooling hoses and when they removed the thermostat housing, the bolts were so fused with rust they had to replace the housing as well.

Before he began he suggested changing the timing chain since it would be exposed after removing the water pump. Since I don't know the actual mileage due to the 5 digit odometer, I told him to go ahead with it.

He said the timing chain had a little play but not as much as he expected so perhaps the mileage is closer to the 120,000 km I was told it had when I bought it. It's also nice to know it's a pretty rugged double chain that I won't have to worry about again for a long time.

It was expensive work but I have a lot more confidence that it will get us back across the country in August. Especially if we follow Route 66 from LA to Chicago in the heat of summer.

 

[dana44]

So it goes to show the toughness and durability of a Mopar, but at the same time you have the peace of mind it is going to make it home much easier.