Sorry for the long post. I am posting this in several forums to see if i can get it sorted out.

I recently bought a 1994 Discovery that is overheating. Here is the story:
When bought, the truck would overheat when I got to highway speeds, but not really during steady in town traffic. It was diagnosed to the previous owner as possibly the head gaskets.
When I bought it, I had the radiator rodded, and the cooling system flushed. A new thermostat was installed since it did not have one. The problem persisted. My mechanic then decided to look at the water pump (which supposedly had been replaced by the previous owner) and discovered that it was corroded and it had a plastic cap (large one--around one inch in diameter) inside it (it’s a mystery how it got there). We replaced the pump with a new one. The other components of the cooling system seem to all work fine (fan clutch, etc.) and I don’t seem to be loosing coolant nor does there seem to be any in the oil.
Then the alternator gave out, leading us to think that maybe the auxiliary (electric) fans were not working properly for lack of enough current. After replacing the alternator, the problem persists, but different. The truck will keep temperature fine (gauge at 9 o’clock position) for up to 20 minutes of highway speeds, but when I get to driving at 20-30 mph, the gauge first creeps up a few millimeters and then at the next stop sign or red light, the needle will move up quickly to at least 3/4 of the way up, sometimes more, close to the top white line. By quickly I mean the it almost matches the rate of movement of the rpm gauge. The last thing that happened was that the top (upper) radiator hose sprung a leak last saturday; that was temporarily repaired by cutting the hose and using a metal couple.
And then sometimes I can drive a half hour or so and nothing unusual will happen.

Any ideas?
Thanks

Alfredo

 

Move to Alaska.

This is a tough one, I am leaning towards headgaskets because you blew the upper radiator hose, sounds like it got overpressurizes and blew.
Have your mechanic to a exhaust gas test on your cooling system, there is a dye that they put in the radiator and it turns to a different color if there is exhaust gas in the coolant.
He can also put a pressure tester on it and then run the engine to see if it is building to much pressure inside the cooling system.
PLEASE let us know what you find out.

 

Hi there,
I have a simialr story on my 95 Discovery 1. Everything is similar except that I have not blown a radiator hose and have not rodded out the radiator. I had the radiator flushed. The temp stays fine when I have speeds up but if I slow down it the temp can go up very quick. I was going to get a new radiator or have my radiator rodded out but don't want to pursue if it doesn't make a difference. If you find success, please share what you discover. Thanks so much! If I find anything that works, I'll pass on my news as well.
Drake
Drakesemail@aol.com

 

I had an Acura Legend a few years back. The C32A1 engine in it was prone to head gasket failure. Long story aside, after much head scratching (& some similarities to your symptoms) I figured out I had a VERY small head gasket leak. At idle & low RPM a small amount of coolant gets sucked into the engine, at higher RPM the pressure forces out of the system, most likely into the expansion tank keeping it full, therefore it appears to not be losing any coolant. But if you actually open up the radiator filler hole it will probably be low or almost empty. (wait till engine has cooled off) Thus giving the erratic temp gauge readings because of the air in the system. I went through this for a few weeks before reading some info on the Acura Legend forum and finally figuring it out. My expansion tank always stayed full, then a couple of days I'd been driving hard on a hot day I noticed it overflowing & the pieces started fitting together in my head. Because of the slow leak the system will not suck coolant back from the expansion tank into the radiator when it cools down. Try checking the coolant level in the radiator directly every morning before you start the car when it's cold. Top up as needed and monitor closly, IE every time the truck is cool enough to open the rad cap. Keep it topped up in the rad and see if the engine temp stabilizes while running? You may need to bleed the system too. Once I figured it out I ran the car for a few months by just daily topping up the coolant every morning. (about a pint a day) The erratic temp readings stopped then. But ultimately, you will need HG job at the minimum, with the rover motor you may need a whole new engine if it's overheated and the cylinder sleeve has slipped. I could aslo smell an exhaust/gassy smell right as I opened the radiator if you get your nose over it.

 

UPDATE

My apologies for not having updated before, but I was still trying to figure out what the overheating cause was. (I paid close attention to all opinions graciously given by all of you).
In the end, I listened to my mechanic (who swore that it couldn’t be the engine because it didn’t always overheat) and took it to a different radiator shop. They called me today to show me that when they fed water to the radiator (on the ground) through one end, only about 40% of the lines had flowing water on the other! (I guess the first radiator shop only told me that they had rodded the radiator but didn’t actually do it).
At 7:00 pm today I received the truck back and they told me to “test it out the way you want to”. So, I proceeded to drive approximately 34 miles at speeds of anywhere from 75 to 90 mph (except for about a quarter of a mile where I drove 65, the speed limit, because there was a patrol car). After driving it on the highway, I drove it for a little bit in town, parked it and left the engine running, drove it in town again, parked it again and left it running for about 15 minutes with nary a movement from the gauge, stuck at the 9 o’clock position.
My conclusion (and please correct me if I am wrong) is that (thank God) the engine is healthy, and so are the head gaskets. It seems that it was the radiator being clogged all along.
If anything changes (..sound of knocking on wood...) I’ll report again.
Sorry for the long post and thanks again to one and all!

Alfredo

 

THANK YOU THANK YOU THANK YOU for posting the repair.
We are all glad to hear that your Rover is now healthy and running well.
Continued best of luck to you and your truck.

 

Check your water pump, that sounds like your problem to me. At highway speed the engine is turning fast enough to move fluid plus air flow through the radiator to keep the engine cool. At slower speeds your engine runs slower which means your water pump turns slower. A healthy water pump will continue to move adequate fluid even at slow speeds. A failing water pump won't.

 

I was gonna say clogged radiator until you siad it had been rodded. I hate shops that tell you they do it, and don't.

 

Thanks so much for all the great information! I will be taking the radiator in next week to get rodded out. If that doesn't work, time to look at the water pump!

 

How many miles Duck?