Hi guys, I have been lurking on this forum for the last while as I was interested in a Rover for a 4x4 ride and project and took the plunge and bought one today.

The Rover I bought is a disco 1 that the previous owner had been recently experiencing overheating problems. I got it as abit of a gamble as I am relatively mechanically inclided (rebuild a couple cars) and figured I would try to diagnose the problem and see if I could fix the truck ... If I can't it has a brand new set of tires w/ a full spare, probably a couple hundred in scrap medal, and some other parts which I think I can sell to fellow owners to at least get my money back to find a new one (I only paid $900 for this one).

My questions that hopefully someone can help with :
1) Obviously my biggest concern is that the previous owner had overheated more than the seller led on and the block cracked or warped to an extent that it is not worth machining/repairing; however, while driving before the overheat (about 5-10 mins) the truck runs well - lots of power, no problems starting, good acceleration, sounds smooth - what is the liklihood a rover with a blown engine could run with no major problems?
2) After it heated up to the red during my test drive and we quickly pulled over to wait for it to cool, I opened the hood and tried spinning the fan - spun with no resistent - this leads me to believe the fan clutch is dead, however, I find it hard to believe that this alone would cause an overheat while driving even at close to highway speeds .... Am I wrong in this thought?
3) Even when hot and running, the upper rad hose is very soft to the point I doubt there is any fluid flowing through - is this normal on these vehicles? Obviously if the thermostat was broken shut this would occur and explain overheating but the seller seems like a reasonably smart guy and as such I highly doubt he would have sold a vehicle for <$1k when all it needed was a new thermostat ....

I am hoping that I can get this cooling problem figured out ... If so I am planning on doing a rebuild of the engine (very gunky, I don't trust it and I need a winter project) or at least pulling it to do a good clean and replace the gaskets and inspect the bottom end and heads for any issues and doing the 60k maitaince per the stick in the tech section but before this I want to make sure I can get this things to run without overheating! I generally don't like sending a car to the crusher with fresh oil and transmission fluid.

Wish me luck and thanks for any insight you guys can provide.

 

Does the fan turn when the engine is running? Thermostats are easy on these to check and/or replace. Even when replacing a thermostat I check the new one. I get a small pot of boiling water going and drop it in to see if it opens then remove and cool to make sure it closes. Another thing mentioned in here and has happened to me, the vent hose from the drivers side valve cover to the intake (about 6" long), if it clogs it cause the oil to heat and oil leaks and higher temperatures.

 

Lots of things for you to check.

1. Is it a Discovery 1? For my notes, I assume a D1, much will also apply to a D2.

2. Red area is cooking. Normal is 8-9:00. Above 9:00 is way 2 hot by most standards. Moral - gauge is designed to keep nervous Nellie out of the service department. Plug in a scanner or Ultra Guage (a slick $70 gauge/alarm, scanner/ code reset device UltraGauge Automotive Information Center and OBDII Scan Tool) and see what temps are exactly, so you will know if you are making progress before overheat. My gauge stays at 8:00 - 9:00 from 135 to 235 F....

3. Stock stat is 195. Toss it, install a 180. There will be purists who say this will hurt your gas mpg. Let us get cooling system in tip top shape, without more engine damage, you can switch back later. 160 is do-able, but you will have minimal heat, not advise. See pix of stat opening. You want the vent jiggle device aligned to top of hole, it passes gas bubbles and keeps stat body in hot water, instead of steam. You want fast reaction of stat. Think of it as a boiling pot of pasta. Hold your hand over it. Now put your hand in the pasta. Which makes a faster reaction? (lol). BTW, no stat on mine does 135 - 145.

4. Fan clutch is toast if when warm it will spin more than 1 revolution when turned by hand and released. You can buy a new one that fits a Chevy van 4.3 liter, NON-AC, and use that. Good write up in our tech section. Or you can buy a junkyarder like I did, for $20 (with larger fan) - the late 90's - early 2000's of GMC and Chevy use the same 6 inch clutch, reverse rotation, and thread to our water pump. I get about 6 - 10F improvement in 100+ F weather. Mine moves a lot of air.

5. Speaking of reverse direction, check belt route twice. It is a frequent goof, and water pump runs reverse and you over heat. See tech section or the RAVE shop manual set (free download in my signature). Cupped side of fan blades go toward block. A wimpy plastic bag held in front of grille should be sucked toward engine. In addition to bad belt route, my PO had revese wired the electric fans for the AC condenser, they subtracted air flow, and I would overheat at idle. Plastic bag blew away from engine with just AC fans on.

6. One likely culprit is clogged radiator. The D1 has a $600 copper and brass radiator, easy to take out. Fnd a small indy rad shop that works on tractor and heavy equipment radiators. That is where they make their boat payments. Take yours in, don't tell them Rover if you don't have to (some people switch to MSRP pricing mode "Make Sure Ream Prospect"). Hot acid flush and unsolder a tank and rod out the calcium build up is about $70 - $100. A poor flow rad will have gunk in lower rows, and be cool at the bottom. Added gallons of "stopz leekz" to resolve over heat issues simply sink to the lower rows and block off more cooling. My rad guy says a good rad won't vary more than 10 degrees across the surface area.

Rad has tranny cooler on driver side and oil cooler on battery side. I had a used rad with a plugged oil cooler, oil light would not go out while dumb me had my head stuck under the hood looking for water leaks.... always wait for oil light to go out before moving away from driver's seat...

There is a space between rad and AC condenser, gets clogged with mud and trash. Should be able to shine a light through the fins.

So, once you know how hot it is getting (without going past 212, no need to go further), you can begin your attack. An IR thermometer is handy to have as well. In the stat hole pix you see two devices to the right. The single wire one is the gauge sender, the two wire square top one is the coolant temp sensor that shows up to the ECU and the scanner output.

Running right you should be able to get stat marked temp +/- 3 degrees when at highway speed on level ground. At idle, may warm up as stat opens more (stat marked temp is where it starts to open, full open is 15 degrees more approximately). So with a 180, I can make 180 - 183F at 2000 rpm on level road.

From your descriptions I believe that you have multiple cooling problems.

We have not talked about water rushing sounds under dash. If heater hoses are hooked up, and you hear that noise, bubbles are flowing around inside cooling system, you need to purge these. If they return - could be an indicator for head gasket leak. There is a $50 chemical test for combustion gas in coolant you can buy at NAPA or various parts stores. Are you having any white smoke after warm up, any loss of coolant, coolant in oil?

Change oil to Shell Rotella 15W40, you need a W40 oil, and the diesel rating does a better job of cleaning out the engine. Overheated oil is thinned out.

 

The fan does turn when the engine is running but when hot and off it effectively free wheels which makes me believe is is broken.

Until I diagnose this problem, I am probably going to take the thermostat out - I know this is not ideal and can cause somewhat higher temperatures but until we find the big problem here I want to take as many variables out of the equation as possible. Also, having to warm up a vehicle to check coolant flow is time consuming and I believe dangerous in this engine since it is prone to overheating.

 

Thanks for the extensive information and detailled reply.

1. Yes this is a D1 - 1996 to be exact - yes I knew before buying this is a problem year but the price was right and it is a good project nevertheless.

2. I am aware of red being too hot and we have attempted to kill engine as soon as > 9 o'clock. My concern is the other driver doing permenant damage (i.e. that that can not be fixed by a modest amount of machining/internal component replacement). From reading this forum, people seem to say if a vehicle has overheated a couple times the engine can easily be toast - I am wondering if this is still likely for my truck given the engine appears to be running strong still before overheat.

3. See my post above - Does this seem okay to you? After (if) we get this figured out, I will replace with 180F as recommended.

4. Thanks. As I expected. We will try to find one per the guide on the forum at the wreckers and replace. One theroy I am currently having is that the previous owner overheating issue was caused by a dead fan (i.e. overheating at idle) ... From this overheating problem (likely while in traffic) he shot out some rad fluid once the overflow tank filled ... after this, if he just dumped more glycol into the rad (and didn't blead it) each time it overheated there could be a significant amount of air in the system ... this would explain why we are now getting overheating even at highway speeds. My plan therefore is to replace fan (as it almost certainly shot), pull rad and bring to shop to check it over and repair as necessary, and then do a proper fill with distilled water (don't want to burn through too much glycol at this point as each bottle in Canada is about 2% of the cost of the vehicle ) ... After I get the rad filled and bled, I will start it up at idle and see if the new fan and rad clean make a difference - while doing this I will do the chemical exhaust gas test to see if any gas is getting in and go forward based on the results of the exhaust gas test and the change in overheating from the fan replacement and proper fill.

5. Checked twice ... belt direction appears okay.

6. Inspected for mud etc and no issues. See 4 above for plans to get rad checked out - I will follow your recommendation of avoiding the mention of it being from a Rover....


The previous owner had originally thought the heater was plugged and was causing the problem (I do not see why this would have mattered as from my understanding the fluid does not need to run through the heater to cool the engine ....) and therefore he has it disconnected... I am planning to reconnect and therefore will be able to tell when I do the stuff mentioned in #4 above if I am getting this sound ... however since I am also doing the chemical test I probably will find out if exhaust gas is getting into the system this way anyway.

Didn't notice any coolent in the oil when I checked. Hard to tell for white smoke since it is freezing outside, normal exhaust is almost like white smoke from every car

Thanks again for all the help and I will keep posted on results.

 

I wory about people using the stock gauge as an indicator of "it is fixed now" because the guage reponse is so broad. If you can borrow a scanner that reads live data, or justify having one to service your other vehicles, or perhaps the parts stores will read for a code for free like they do here in the US.

That is part of the idea of using a 180 stat while testing, if not always. If engine and rad are normal, it will stay a 180 - 190. If it hits 200, no need to keep going, it a'int fixed yet.

Blown head gaskets can be caused by overheating, and a more serious condition, the slipped cylinder liner. And blocks can develop cracks. Normally these have other indicators, like coolant loss, leaks of coolant on to ground, into oil (makes it milky), ar out the tail pipe (white smoke that does not stop when warmed up). The steam being released inside the motor makes a gurgling sound under the dash as bubbles swish by in the heater plumbing. The upper hose can become rock hard.

If these symptoms have not shown up yet perhaps you have the garden variety overheating. But frequent overheating can warp the heads, and cause the HG to leak. The spec for "flatness" of the head is .002 inch, and your printer paper is about .0038 inch thick, so it does not take much.

IMHO if you can operate engine at a temp where steam, gurgles, and overheat spikes don't happen, you can drive truck while you decide on what steps to take next.

Would not just take out stat, but would replace it with a 180F one, about $6 - $10 US. If the one you get does not rattle or jingle, then it does not have a gas vent built in to the edge of the stat. You can drill a 1/8 inch hole in the flat edge of the stat to do the same thing. You can also test the stat you have by removing and placing in a pan of water that you bring to a boil on the stove. Then all you have spent is money for a gasket, if stat is good. Pix of boiled stats and an old stat with a vent jiggle gizmo in the flange.

You'll need glycol to keep engine from freezing and popping out freeze plugs or worse. It is OK to re-use the coolant you drain while doing the work. The heater being bypassed removes the water rushing noise. If bypassed with a single "U" shape of hose, OK. If bypassed with two "dead ends", that would not be desired. See attached pix.

It is a good sign if truck will idle for 10 - 20 minutes without over heat. In addition to a clogged radiator, a worn out water pump could cause problems.

 

Valid point about the stock gauge and I realize that the one in the car is very rough ... Maybe I will have to invest in one.

My only thought about having the thermo out while testing was that it would allow me to see if the system was flowing as soon as it was turned on but i guess that isn't critical - once I know it works, I can move on to something else.

As I mentioned I bought the truck expecting the need for an engine rebuild so I am not surprised if this is the case. If for anything else, taking it a part and visually inspecting and checking tolerances will give me piece of mind - even if I can get it running and not overheating before taking it apart. I do not notice any coolant leaking in the 10 mins before it overheats - after it overheats there is obviously a pool on the ground from the expansion tank overflow within the engine compartment but I dont believe this to be a leak. The oil didn't show any contamination. I will run an coolant chemical exhaust gas test when I'm at my shop in the upcoming week.

The idea of using distilled water instead of glycol for the troubleshooting is because I have a heated garage (not a huge risk of overheating) and prefer to get water on the ground when flushing and if the tank overflows than glycol. With prior vehicles I have used water until I was confident that the system was working properly, had no leaks, etc. I would then drain enough to put the required 50/50 mix into the system. Do you think this would be a problem in these conditions?

Regarding the heater - the previous owner has bypassed it and correctly connected the in and out cables from the heater together.

 

Speaking of the temp gauge - does anyone have any ingenious ideas of a place where i could just install an old fashion capillary tube gauge in the engine bay? I have some of those lying around the garage ....

I was thinking of screwing one into a piece of PVC and putting it inline with the lower radiator hose but the problem of this is 1) I won't get an accurate reading at all if I am not getting proper circulation and I have not yet confirmed I am and 2) I do not know how different the rad temp and block temp are and the latter is what is of concern.

 

Garaged makes it no problem. Of course, thermostat must fit into block correctly, the spring goes inside the block.

If the expansion tank is venting thru the cap, that means system is getting to 18 PSI or so. If not wet around cap, and tank is leaking, could be bad tank (espcially if black rather than white plastic version), could be loose hose connector on bottom of tank.

Running with no stat for testing is OK, but will make engine perform strangely (it will run rich trying to warm up).

I have often wondered if we could run these just like boat owners do, with water hose hooked up like in the pix below, letting cold water circulate in, and loose top hose to let it escape. If it can't keep engine temp down, then problems would not seem to be radiator.

I have used an IR thermometer and found the outet for the upper hose to be within a few degrees of the coolant sensor reading.

I would suspect you could insert your test point on the heater bypass hose. It circulates coolant even if stat is closed.

 

I really like the idea of running it like a boat heat exchanger .... grab a huge bucket of water and put the lower rad hose in it ... put the top rad hose in an empty bucket and start it up .... Leave a garden hose nearby to keep filling the cold side bucket as it drains down (yes I know you shouldn't use tap water in an engine but I will do a flush if I can work out the problem). The benefits of this test are:

1) Rule out water pump problem - if water gets picked up from pump water pump is good ...
2) Allows me to eliminate the need for the fan (which I know doesn't work) and the rad ... If the engine runs continually with rad not connected we know the problem is the rad/fan ....
3) If cool water is getting picked up by pump and still overheating, we are likely looking at an internal engine problem ... i.e. head gasket leak

Do you see this causing a problem? Will the air in the system cause a problem given there is no pressure being created? Providing the in and out hoses are both covered in water we should get enough pressure right? Part of me feels like there is no reason this won't work but the other part of me feels like I am overlooking something ...