1995 Disco Overheating Again

[Trey]

Hi Guys,

Would you beleive my 1995 Dico is overheating again. I started a thread about thirty days ago where I stated that I had a bad oil leak and that the Disco was overheating. Well the oil leak is fixed and I fixed it with you guys help, but the overheating problem is back again and thats what I thought the dealer fixed LOL. I guess you guys can walk someone through a fix better than the dealer can fix things so here I am again LOL. My Disco does not appear to have a coolant leak but my coolant is going somewhere because every three days I have to put coolant in the resevoir. The temperature gauge increases as my rpm's climb above 1800 (about 40 mph). The fans seem to be opperating and the temperature goes down as I slow down. I have never seen anything like it. I repeat I do not see any coolant leaking anywhere and theres nothing on the engine I don't even have a coolant burn smell. Where is the coolant going. After the dealer flushed and drained the radiator (They said the radiator was fine) it ran fine for about 5 weeks. Could the radiator be clogged again or could it be the Thermostat or Gauge Temperature Sensor and where are these located on 1995 Land Rovers.

[downunderdisco]

It maybe a head gasket. How does your engine oil look?

[Trey]

The engine oil looks fine and theres no leaks no oil or coolant anywhere on the engine.

[TerryS]

I have seen loads of Rovers with the "loosing Coolant " problem, and I have never seen the cause of the problem manifest itself with oil/water mixing. This is because when a head gasket blows, it is never in close enough proximity to the two (one on each head) passageways where oil passes from block to head.
Coolant flows from block to head at the extreme rear of the heads, through a rectangular port, between the last two headbolts. The vents are between the first two headbolts. For reasons unknown, the headgaskets almost always fail at one of the four corner cylinders, on one side or the other. The failure is, 99% of the time, between the bore and either the vent hole or main passage, but so small that either water goes into the cyliner, and then out through the exhaust, or combustion pressure passes through this leak, and over pressurizes the cooling system, causing coolant to be blown out the pressure relief cap.
The reason it does not show up as water in oil, is because the oil passageway is between the first two cylinders of either side, and this passageway is a good half inch away from the cylinder bores. (but very distant from the four water passageways) Oil draining from the topend goes down the pushrod areas, outside of the headgasket area.

When water leaks into the cyliner, it is almost always after you shut down, when pressures goe to zero in the cylinders, but pressure still exist in the cooling system. or, in the case of over pressurizing the coolant system by combustion pressure, when you ar at running speeds (as opposed to engine idle speeds.)

Compression tests, and leak down tests are not helpfull and almost always lead to the belief that it isn't a head gasket.

One very good indication is removing all the spark plugs and comparing their color. An exceptionally clean looking plug, compared to all the other, is usually a good indication that it is getting 'steam cleaned., Another is the appearance of what seems to be an excessive amount of water vapour from the exhaust pipe.

Head gasket failures are rectifiable. The worse situation is when a cylinder liner to block seal has failed from an overheating event. Because of the mass difference of the thin liners, and heavier block casting sections, and the difference between the coefficient of expansion of aluminum (block) and cast iron (liner) the two expand more than normal when the engine overheats, but do not relax at the same rate on cooling, breaking the seal between the two.
Resleeving is the only option in saving the block, and, to my knowledge, no one is making a practice of doing this in the US. There are specialist firms doing it in the UK, but installing liners with a lip at the top, into a newly machined counterbore in the top edge of the block.

[Disco Mike]

Terry is right on the mark.
Sounds like you need to go to your favorite shop and have them do one of two checks for internal head gasket leaks, a chemical test on the coolant system or sniff it with an emission tester to pick up any exhaust fumes in the coolant. If either of them test positive, you should probably do a compression test to verify your findings.
Mike

[Rovin4life]

Terry, I had a 2002 mercury Villager do the same damn thing to me.

It came in overheating. I bled the system worked fine. test drove it cold, overheated. Put a thermostat in it. worked fine in the shop and on test drive.
Overheated when customer took it again. bled system, fine and dandy. performed a battery of tests including leakdown, compression, and even check for exhaust gas in the coolant after it warmed up. Still nothing. Finally took it ofr the night and found out it would only overheat when you took it out when it was cold. If it warmed up slow it was fine.

tore the motor down to the cylinder head gaskets. never found anything wrong but I was one step away from a motor and a buyback. Needless to say it worked.

So the moral of the story is, if it heats up fine when you let it heat up slowly and overheats when you take it out and drive it from sitting overnight.

Its the headgaskets.

[pavel]

Ok, if it is head gaskets (I replaced mine just over a year ago during a decoke ceremony)....Why? This engine started out as a Buick power plant in the 60s - you'd think that by now, every conceivable problem would have been worked out! The Japanese can build an aluminum engine that lasts, so what's the problem.
What I am working up to here is this: assuming the emissions laws allow me to do it, what replacement engine should I be shopping around for so that it is ready to go in when my 4.0 fails? I'd love to go with an older Mercedes Turbo diesel...
Sorry gentlemen, I just think these failures/problems should not happen. Oh yes, one more thing: can you O-ring the tops of the cylinders, as was possible on older V8s, to make a better gasket seal?

[Militant-Grunt]

Mine overheats aswell, but only after the reservoir is near empty, second time this month that I refilled it, I have no idea where it is going, I dont see any leaks.

[Adam in NYC USA]

Just had the bottom radiator hose that looks like a fallen branch break on me last night.

When you go to the auto store at suppertime, don't expect to find duct tape there. I had to buy serveral gallons of anitfreeze to make it back to the shop. I lucked out that the local Indy Rover shop was 1. late open and 2. had the lower hose.

One bitch was the hoses going to the overflow container. Second was getting all the air out of the system. I aint satisfyed until the thermostat opens up and then you get the heat inside the passenger compartment.

I am making a guess too that you have trapped air up in the back and before you pressurise the system, let it run with the vent open on the radiator until all the air is out and then let the reservior do its job.

But before anything, no leaks under the overflow reservior?

Adam in NYC

[Disco Mike]

Originally Posted by Militant-Grunt

Mine overheats aswell, but only after the reservoir is near empty, second time this month that I refilled it, I have no idea where it is going, I dont see any leaks.

You have been around long enough to know that you can have a coolant leak on a Rover and not have it show.
I would suggest you go have it tested. There is an old saying in the car business," Pay me now or pay me later", the problem is later is always more expensive.
You are most likely burning off the coolant because of a head gasket failure.
Mike

[apbtpetey]

I agree it sounds like a head gasket. I had the same problem with losing coolant, but not finding where it was going. I had it pressure tested at a local shop and sure enough it was leaking from the rear driver side lower bolt.

Replacing the head gaskets isn't to bad of a job on these engines. My heads were fine and it never overheated, so without machine work it took a weekend to do, could have had it done in a day if I pushed myself, but I ook my time and cleaned things up all nice.

[wade]

This may be really lame..I'm a novice at LR repairs, but the coolant tank on mine was leaking at the seam at one point and I replaced it. It is difficult to see the leak since it is generally steam bleeding out.

Before that the water level was dropping. I suppose it is cheap enough to check.

[Adam in NYC USA]

Originally Posted by wade

This may be really lame..I'm a novice at LR repairs, but the coolant tank on mine was leaking at the seam at one point and I replaced it. It is difficult to see the leak since it is generally steam bleeding out.

Before that the water level was dropping. I suppose it is cheap enough to check.

Good for you.

It is human nature, however. I am an Emergency Medical Technician and part of my job is doing detective work based on objective and subjective evidence (don't worry people, I can explain those big words; my favorite big word is frankurter, myself). Objective is what you see; subjective is what the subject is complaining of.

One of the things you can count on is that it is usually the simpliest stuff that bites you up (or down) in the bum. I check the hosen before I start pulling the intake mani off.

Second thing, it is usually the hidden stuff that bites you. Many people get hurt in a car accident and dont realise you can have a ruptured spleen. It can happen if you have a tight seatbelt, it could be that you injured it walking into a table and then rupture it into an accident.

Another thing. there is nothing wrong with trusting your senses. Just believe in yourself and your senses.

Again, good luck, grasshopper, and learn and kick ass.

Adam in NYC