Jaf15 Posted March 14, 2018 Share Posted March 14, 2018 Hi I'm new to this forum and was wondering if somebody could point me in the right direction. Recently I have bought a discovery 3.9 v8 and I appear to be having some issues with it overheating. This only seems to happen under load climbing fairly steep hills or in low box. So far I have changed the thermostat to an 88degc from a 92degc. Fully working as I heated it up in a pan over the stove. I have also changed the coolant and also cleaned any debris out of the radiator with the garden hose. I have just also changed the viscous fan coupling as the fan did not seem to be kicking in as it should and there was little resistance on the fan. The coolant system was bleed up after putting the coolant in. i took it out tonight after replacing the viscous fan coupling and all seemed ok until I went up a long incline. I pulled over before the needle hit the top line before red turned off and got out.. opened the bonnet. The engine did not feel hot hot I could put my hand on top of the air intake for ages without any concern of burning my hand. Could this be a dicky temperature sensor? Anyone had anything simular? Please help.. 😐 Quote Link to comment Share on other sites More sharing options...
110 V8 Posted March 15, 2018 Share Posted March 15, 2018 Does it lose water, blow water out header tank vent? Or just read high on gauge with no other symptoms? Andy Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 15, 2018 Share Posted March 15, 2018 Is the stat a genuine one with the jiggle pin at the top? A new temp sensor for the gauge will cost all of a fiver so might be worth just doing it to rule it out. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 15, 2018 Share Posted March 15, 2018 Get an IR thermometer and actually check the temperature. Will be useful for other things in the future as well. Can also check radiators for blockages with them by testing different areas of the core. 1 Quote Link to comment Share on other sites More sharing options...
ballcock Posted March 16, 2018 Share Posted March 16, 2018 Has it got air-con? If so is the alloy radiator blocked or the radiator filled with debris? I had this on one of mine I removed the air-con rad and problem solved, the alloy had deteriorated and not allowing enough air through to the rad, Not a case of overheating more a case of under cooling. 1 Quote Link to comment Share on other sites More sharing options...
Hercu Posted March 17, 2018 Share Posted March 17, 2018 7 hours ago, ballcock said: Not a case of overheating more a case of under cooling. Hi Jaf Agreed with Ballcock Not knowing your location but here in Southern Africa the stock radiators do not work due to the bypass hole in the main radiator tank, If you remove the bleeding screw on top of the radiator (hope yours is brass) and inspect by putting a "welding" rod you will find about 20 cm down a partition with a 20 mm hole which allows warmer water to circulate straight through on cold starts..You might be able to see it by lighting a torch into the hole... In warmer weather 30 to 40 Deg C the water is taking shortcut and does not circulate through the cores of the radiator,,, I had mine cleaned and hole blocked by Radiator guys and never had a "Under cooling" problem again and sometimes I drive in low range thick sand for 2 hours at 25 kmh, with ambient 40 deg without the heat gauge moving from normal.. PS: did remove the air con Rad as well and fitted new viscous fan...! 1 Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 20, 2018 Share Posted March 20, 2018 Well I just learned something from Hercu - never knew that about stock rads! 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.