View Full Version : D90SW overheating.

02-17-2007, 02:32 PM
My D90SW has been overheating fairly quickly since last year. One suggestion is to have my radiator flushed or replaced. Another to have my thermostat replaced. Another suggest checking the cooling fan. Another suggestion...lots of suggestions but I really need solutions. Please advise. Thanks.

02-19-2007, 02:23 PM
I had an overheating problem in my D90 and did everything but pulling the heads, even checked for exhausting in the coolant several times (ie head gasket leak). One day I was stopped at the local LR shop to pickup something and left the engine running. I was getting ready to pull away when the mech came out and told me I was dumping coolant, the temp gauge wasnt showing a high temp. The motor at undetermined times would develop a head leak on from the exhaust and pressurize the raditor blowing all the coolant out, the engine would then overheat because of no coolant. There was no coolant in the exhaust or exhaust in the coolant.

I would proceed in this order: Use a laser thermometer to look for hot/cold spots in radiator (recore/replace if problem found), change T-stat and coolant, check sensor/gauge/electrical, check fan, look for exhaust in coolant and coolant in exhaust and lastly pull heads.

02-21-2007, 02:13 AM
Another problem some forget is that if your catalytic converters are clogged up , they can cause an enormous amount of heat to build up causing your engine to overheat (especially at rest). I would replace them if you have over 100,000 miles. Hope that works. Let us know what it is when you find the problem.

Mike Koch
02-22-2007, 03:21 PM
If it's overheating while idling, but cools down at highway speeds, it's probably your fan clutch.

In regards to the clogged cats, I recommend installing new oxygen sensors at the same time the cats are replaced to ensure maximum longevity.

Just my $0.02,

Mike Koch

02-23-2007, 05:35 PM
Thanks for the feedback, gents.
I wasn't forthcoming by not providing more details of what I describe as overheating. In my last trip- NYC to DC, I had to pull into a rest plaza along the NJ trunpike due to overheating- the temp gauge did not venture into the "red zone", while stuck in traffic. 15 minutes later,we tried to continue with the journey when my vehicle refuses to start back up. Tried several times to no avail and it only started up after an hour or so of "cooling down". This has happened about 2 or 3 times. Since then I notice the temp gauge is quick to get up close to the red zone especially when I am caught in traffic or driving around in the city.
I will defer most of your suggestions to my mechanic and to the folks at RoversNorth. Thanks again.

02-24-2007, 10:15 AM
Your restart problem is likely due to a heat soaked starter. This is fairly common with number of GM designed V8s. Land Rover fitted a heat sheild on some to help with the problem.


04-16-2007, 11:48 AM
I've just come across another cause for some odd Defender over heating.
This applies to all that have the metal expansion/over flow tank. It seems that the lower hose to the tank can become plugged (it is quite small) and this may cause an airlock in the coolant system.

04-16-2007, 01:26 PM
Here's another possible thing to look for. On my old '94 D90 we were growling along Hwy 80 through Nebraska pulling a Taos camper and fully loaded, on the way to the Solihull Nationals in 2001. It was HOT outside (in the high 90s) and of course I had A/C on full - not that it helped...:sly: Driving into a city, we had to slow down and I noticed that the temp guage was going to peg itself and go into the red zone. Crickey!

Once we got going again, I pulled over to at a rest stop, called Les back at RN to help diagnose, and in the process found a ground wire hanging by the front radiator panel near the brush guard. While the engine was running, I touched this and the A/C fan lit up for a second! I loosened up the brush guard 17mm mount and tucked that ground wire in nice and tight. It was an easy fix, but one that would have required running in those hot temps for a long time - something that never really happens up here in Vermont - because my driving distances are short and it's cool up here.

Ray Bone
04-29-2007, 02:04 PM
I had a same problem with the overheating, then i recored the radiator and changed to 4comb , my overheat issue stop.

Robison Service
04-30-2007, 06:59 AM
I wrote an article on Land Rover overheating in the Rover News. Look through the archives here, or look on my site, www.robisonservice.com > service > land rover > articles

04-30-2007, 09:05 AM
Here is the direct link for Robison on Rovers PDF file (420k) "Preparing for Summer Driving" (http://www.roversnorth.com/web/downloads/rnnews/NSP64_pg2_3.pdf)

05-06-2007, 11:27 AM
To all who has replied to my posting. To update, the radiator is one o the main culprit according to the mechanic. To that we weren't able to order a new on as it turns out, radiators are on a worldwide back order. Hmm, something to do with the war in Irag????
Anyway, we are having it recore and at the same time replacing items like the thermostat, oxygen sensors and etc.etc. Thanks again.

06-16-2007, 03:34 AM
On my 94 D90NAS I had the aforementioned problem where the head gasket had a small leak into the cooling system causing bubbling in the coolant then the contents of the system would puke out. Got that fixed. Still nearly overheated in traffic on hot days all the time.

Ended up being the fan clutch which I hear is very common. Ordered a new one and installed it myself WITHOUT the lame and expensive spanner set made just for this pupropse.

I snuck a 12 inch Crecent in behind the fan onto the fan clutch nut. Be careful not to bust the fan, as I hear they are fragile. I then stuck a leather work glove between the belt and the water pump pully and turned the wrench clockwise (the nut is reverse thread) until the glove stuck in there good enough to keep the belt from slipping on the pully. I then gave the crecent a light smack with a small sledge hammer and the nut spun right off. Put the new one on, and it runs cool as a cucumber now.

I did it all in about an hour, and I have almost no mechanical skill (regular maint is about the best I can usually do).

I hear this is a common issue, so even though the part was over a hundred bucks, I saved on the labor. Also, solving the overheat will prevent more head gasket damage and/or a slipped cylinder sleeve in the future. Overheating at idle=Fan Clutch very likely.

06-19-2007, 11:06 AM
A quick tip: fan clutches do not not like deep water crossing as the extra work of pushing water can burn out the clutch. Of course even if you never get wetter than a heavy dew you can still have fan clutch troubles.