hello everyone.... im new to the site as well as new to owning a land rover!!! ive had it for ten days now and have only put 50ish miles on it cause it keeps OVERHEATING!!! now i do have some mechanical know how, and after reading some manuals for this truck i understand its coolant system pretty good. ive done a flush, replaced the upper radiator hose, pressure checked it at 20 psi, replaced the coolants with dexcool, hand my hands on the water pump, bypassed the thermostat, the fan is good, all the hoses are good, the lower radiator hose may need some work in the future.

this is what happens.... after about 20 miles, mind you that it gets to normal driving tempature and stays there just nice for a while. then out of nowhere the heat will spike, were talking within a mile i will be redlined. top remedy and make it down the road, i open the header tank cap release this amazing amount of pressure and tighten back up and and i can go for a little while again.

with all this being said, am i looking at a faulty head tank cap and that is it? or can it be more serious. btw ive recently learned that the "mechanic" before me changed the distributor cap and plugs and wires and such, could any of that lead to trouble?

btw, lol, i own a 97 discovery with the v.8i. i love that truck, and the idea of owning a nice 4x4.

i wanna thank everyone and anyone in advance for there help with this. im new to this site but trust me if i can my new toy working right you will be hearing alot from me!

 

oh one more thing when i go into park the rpms sky rocket upto 3 grand. i can make it lay down, sometimes by simply stomping the gas pedal. i didnt know if this was a vacuum line issue, and if so may it be relavent to the overheating?

 

Number ONE -GET the DEXCOOL out of there. It is an aluminum engine and DEXCOOL is not what you want in there. You will ruin it.

Number TWO: A 97 does not have a distibutor! 95 and earlier have a 3.9 with a distributor. 96 and later have a 4.0 with electronic ignition. Coil packs with a coil per plug.

My "early 97" has the GEMS engine intake that is a large rectangular intake. Later ones have a much different intake with a series of pipe looking things on the top of the motor.

Discoveries are notorious for bad head gaskets. If you just bought yours and it was really cheap, be prepared for lots of problems that the PO did not want to deal with.

 

Do you have access to a laser pointer thermometer. Raytek makes the minitemp and you can get it at NAPA pretty cheap. I would take heat readings of the engine at normal operating temperature to see what is going on. My 99D1 after about 20 miles reads like this: Upper Radiator hose 177 degrees, ECM 113 degrees, Fuel pump relay 136 degrees, Water pump 173 degrees, throttle body 143 degrees, Pas exhaust manifold 625 degrees, Dri exhaust manifold 591 degrees, Pas valve cover 183 degrees, Dri valve cover 182 degrees. Knowing these temperatures helps diagnose potential problems areas. I had an ECU go bad on me and it raised my RPM's. First find out if the system is actually heating. Just going off of the gauge sometimes is not so acturate. Measure the temperature of your heads at each cylinder, this will let you know if anything is out of the norm. Each cylinder should be close in temperature. If you expect a head gasket. You can take readings at each cylinder on the head to determine where the problem area is.

 

it is a coil pack they replaced.... sorry.

 

uhhhh.... this truck is becoming a pain in the butt. i read online that dexcool was what u want. im not gonna argue with ya, what kind would you advise me to use???? as for the head gasket, seeing its sunday and i dont have access to a laser pointer, any other ways besides checking for the tempatures that i can tell its a head gasket?

 

With the engine off you can run your hand around the radiator to find hot/cold spots. Cold will indicate blockage. Have you had the small radiator cap open? What did the core ends look like, crusted? Just use plain ol green antifreeze. When the motor gets warmed up turn off the truck and spin the radiator fan, if it resists then the coupling is good, if it freewheels then it's time to replace. Should sound like you have a super charged motor when you take off. 3k idle is suggestive of the IAC being clogged. Check, clean. They are a learning curve, like everything else worth doing.

 

For what its worth, I have run dexcool in a clean non-leaking cooling system and change it every two years. I have 120k+ miles and it never overheats and when I refreshed the hoses the system was spotless. Dexcool is fine unless you get air in the system or neglect it.

 

Run a mixture of goat, water buffalo & camel **** in it if you want to. It doesn't matter to me. Dexcool is said to react in a negative fashion with these. Something about eating it up. I do not know the specifics and do not really care. Standard green Prestone antifreeze is all you really need.

How are you going to prevent contact with air?

I know some people also recommend a Water Wetter additive. If you service it regularly, it should not be a problem.

 

They have those laser thermometers really cheaply these days. I saw a Harbor Freight ad recently and a sears ad that had them on sale.