[Pardon the lengthy post] A couple of weeks ago the water pump on my 98 D1 (135kmiles) destroyed itself and I had a major overheating problem. After the pump was replaced (belt is properly routed) we had an overheating incident after driving 20 miles at 65 mph (needle pegged-it go so hot the air conditioning stopped working. That's when I sensed we had a problem. What's that all about?). Lost a lot of coolant. Got it off the road, cooled down and dumped a gallon of 50/50 antifreeze in. Drove another 6 or 7 miles (back towards home!) and same thing happened but got the truck off the road before temp got to high. Dumped more antifreeze in and made it home.

The mechanic figured I had blown a head gasket or cracked the head. However after many short trips around town, no more loss of coolant, no visible water in the oil and no visible white smoke. At this point mechanic and I decide maybe a stuck thermostat which he removes. Drove it 15-20 miles today on side roads, 40-45 mph, and after sitting firmly below half way and not budging at all, the gauge begins to go up. Got off the road, cooled down and checked the coolant, it it was fine. Just as I drove in the driveway, the temp started to rise again after being parked below midway up for most of the return trip. But no coolant loss in either case.

What else? Fan clutch replaced 2 years ago and the fan is turning at idle at least. A little tension when turning the and when the engine is cool. Both electric fans work when the air conditioning is on. Do they come on if it is off but the engine starts to warm up? They seem to come on when the engine is turned off. Read something about bleeding the system, but couldn't find mention of it in the RAVE manual and it's not on the tech sticky.

Could this somehow be related to the water pump replacement? I seems kind of odd that the temp will hold fine for a long period of time, then suddenly steadily up. It seems like if there were a blockage somewhere, it would start to rise as the engine warms and just keep on rising. Any suggestions as to what I should look at next?

Thanks

 

If you were getting white smoke you were getting coolant in to the combustion chambers.
Probably a blown head gasket from overheating.

 

As I said in the initial post no sign of coolant loss, no sign of coolant in the oil, no white smoke. So for now I am discounting head gasket/head issues.

 

IR thermometer on the radiator. I recently replaced my Tstat, my water pump, flushed the system, new fan clutch, new E fan, and still had a similar problem, so I gave up and took it to the mechanic where he checked my engine and said no cylinder leaks, then he scanned my radiator with an IR thermometer and found the coolant wasn't flowing "through" it properly, haven't had a problem since. my issue was exactly the same, I could drive 20 miles with no problem and then all of a sudden boom starts to go up, and then once that happened there was no stopping it. for the price of a cheap IR thermometer it would be worth it IMO. I paid my mechanic close to $1000 to diagnose and replace my radiator, it would have cost me under $600 if I bought the thermometer, ordered and replaced the radiator myself, unfortunately I ran out of time and had to have it done right away.

 

Thanks Chris. Sounds like you may have hit on it. Did you get any idea of exactly what was going on? Seems odd that the temperature would hold steady then jump up. If the radiator was plugged I would think the temp would just gradually rise.

Anyone else have ideas before invest more than I want into the beast?

 

Also,a follow-up. Can the radiator be rodded or is that just as expensive as a new one?

 

don't know, my situation was as you said drive it fine then boom hot, I figured it was maybe just progressively getting more clogged because over the week I was trying to fix it it seemed my driving times were getting shorter before it would get hot but I don't know, I asked my mechanic if rodding it out was a possibility, and he said no. Unfortunately I do not know if he said no because mine was too far gone, if these can't be done, or if because he wouldn't make as much money that route. anyways if you determine that is the problem definitely look into options as the radiators on our trucks aren't cheap (mine was I think $650 through the mechanic) and AB.com wants $550 for them on sale right now.something about a 3 way radiator or something, not really sure but some of the other guys on here can help you with that stuff. so to answer your question the best I can, my theory was the same as yours, why would a bad radiator cause a slow temp rise and not just a quick straight to overheating, I replaced all the other components and let my "this just doesn't make sense" thought process prevent me from just looking into the radiator when I had time to order one and have it shipped and fix it myself. so a few hours of paid labor and a little overcharging on the radiator for something I could have (and should have) fixed myself. As for the rod out I think a few of the guys on here have successfully had that done, and a few of those that have replaced the radiators on here have done so for under $400 if I remember right. My advice would be to get the IR thermometer (don't know if you have harbor freight around you but they sell one for $20) then scan the radiator for cold spots, then if it has cold spots start a new thread about radiator questions, what all runs through them?, how to replace them? (do it yourself or special tools or anything), can it be repaired or rodded out? the guys will give you more than enough help with that stuff!

 

may want to look into some flush chemicals too, not sure but just a suggestion.

 

I have seen other guys get theirs rodded out. And I will be doing mine sometime in the future. It will cost me about 80 bucks here locally. Just remove it yourself, take it to a radiator shop, and ask them to check it and rod it. Don't tell them it is a rover radiator or they will flip out. Just tell them it is a (3 core? I think) radiator. At least that is what I have been told. Spike will be able to finish clearing this up as I believe it was him that told me or someone else to do what I said above. Good luck.

 

Sorry, misread, thought you meant "no more white smoke".

Yes you can have them rodded, I've had mine done before.
Keep in mind that if it's gunked up inside that the gunk might also plugging leaks in addition to restricting flow and contributing to overheating.
So once rodded you may find that it needs to be recored, which is still cheaper than new. Assuming the tanks are in good enough shape to accept a recore.