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Discussion Starter #1 (Edited)
Hello DS team! I'm new to everything Land Rover and everything 2.5 NAD. actually, I just picked up this ex-mod '87 110 on Friday and am trying to figure everything out. in the process I can't stop driving the thing.

Today while cruising around town at 60 MPH the temp gauge was starting to run warm/hot. Without any noticeable sounds the shown temp would cool and heat up in wild swings. it might move from right in the middle to 3/4 of the way to the red in three seconds and back again. OR from 3/4 of the way into the red and back. the swings kept getting hotter and hotter near the end of a one hour trip. at the end I was fully in the red and the 'cool' swings weren't dropping back out of the red. Am I about to over heat? is this a thermostat issue? or a pump issue? does the pump run off of the fan clutch?

thanks for the help!

p.s. Is there a consensus for ordering parts here in the US? Do people order parts from ebay.uk?

TIA


 

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Nice looking truck. The best part you can order for your truck is a 200Tdi.
 

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First thing first. Buy what ever owners manual for your truck, at same time buy the parts catalouge for your truck (yes you can download free pdf's of these items). Shot in the dark, im going to say its either your thermostat is going TU or something electrical is going out. I may or may not be intoxicated at the momemt.;) If you dont have a multimeter find a buddy that does or buy one, think you can get a loaner from any auto part store.

You can buy tons of parts from this side of the pond. You are in the middle of this country so I dont know how shipping is going to be for you from the UK.
 

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My Tithonus did the same thing. If you have an IR temp gun, shoot the water pump housing. IIRC temp should be about 130F. If you don't have an IR temp gun, buy one. The piece of mind is well worth the price.

Do you have a water temp gage and an oil temp gage? Do they both track?

I narrowed mine down to the light switch. It was an electrical issue. If it only overheats at dusk, that may be your problem.

Neil
 

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You'll find most parts available here in the US from the regular sources such as Rovers North, Atlantic British, Safari HP, Lucky 8.
 

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My Tithonus did the same thing. If you have an IR temp gun, shoot the water pump housing. IIRC temp should be about 130F. If you don't have an IR temp gun, buy one. The piece of mind is well worth the price.

Do you have a water temp gage and an oil temp gage? Do they both track?

I narrowed mine down to the light switch. It was an electrical issue. If it only overheats at dusk, that may be your problem.

Neil
Just curious if your 130F figure is supposed to reflect that there is 130F coolant flowing through the Tstat housing or if you accounted for cooling?

I have an IR gun and have shot my Tstat housing but I'm getting 180F ish (there is a compatibility issue with my coolant sending unit and my EMS).
 

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I had the same issue in my car recently and it turned out that one of the radiator hoses wasn't on tight. I couldn't see coolant leaking but as soon as it was tightened up it the gauge stopped fluctuating.
 

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Since no one else has said anything, do not drive a truck with the gauge in the red. Yes in the red is overheating and yes you can ruin your engine. You can warp your head and blow a head gasket or worse. A diesel will blow a head gasket quickly when run hot as pressures are twice what they are in a gasoline engine.
 

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yep,sage advice, I'd do that before going and getting my IR gun.
Now why would you want to do that and not go high tec before the simple things? Kill joy....
 

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Discussion Starter #12 (Edited)
My Tithonus did the same thing. If you have an IR temp gun, shoot the water pump housing. IIRC temp should be about 130F. If you don't have an IR temp gun, buy one. The piece of mind is well worth the price.

Do you have a water temp gage and an oil temp gage? Do they both track?

I narrowed mine down to the light switch. It was an electrical issue. If it only overheats at dusk, that may be your problem.

Neil
thanks for the tip! for someone new to the game how do I get a line of sight to the pump housing?? should I take off the fan guard first?

Also, what would cause the swing of temps? does the pump turn on and off during normal operation? or does the thermostat open and close a bypass of the water?? the swing is very odd and I think it will narrow down the problem.


no, my rig doesn't have a oil pressure or temp gauge. only fuel level and water temp.

------ Follow up post added September 7th, 2015 10:35 AM ------

First thing first. Buy what ever owners manual for your truck, at same time buy the parts catalouge for your truck (yes you can download free pdf's of these items). .
this is a necessary first step, but a tricky one. it looks like there have been a number of different versions of this rig with different engines and trims. where can I find a ex-Mod parts catalogue?? that would help tremendously-
 

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You have the simplest defender ever built. The water pump impeller is turning if the fan belt is turning. Most infared temp guns have a weak laser than pin points where the eye is looking so you know exactly what is what temp. No need to remove anything. There are precious few parts on your truck unique to its military spec. Any shop and or part manual will cover your uber simple 2.5 natural engine.
 

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As Doug said. Do not drive it hot. Check with the IR gauge at the thermostat housing. If its over ~190 don't drive it.

If you are not loosing coolant, and the IR gun is not reading hot, my bet is a ground issue.
An incomplete ground on the engine or gauge side can cause very quick swings in temperature readings.
First thing first. Determine if it is really getting hot.
 

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I'm amazed you got it to 60, sure this wasn't KPH? I have found that the older stock radiators were built for the cooler british weather and have a really hard time keeping up with anything over 70 ambient, major problem for me down here in south Florida. Full oil change and blow out the vents, sometimes its the simple things and as Doug says, if a Defender gets into the red - stop.!! Same with fuel gauge, 1/4 tank means panic, if it gets into the red it's too late!!
 

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Do any other gauges give strange readings? your temp seems to be moving very quickly back and forth for me to believe it is reporting an accurate temp.
 

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Is there and Ohm to temperature chart for the standard temperature sender? Id like to see one for the 5/8 UNF that goes on the 200TDi (other engines as well I think).
 
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