B

Bbridge

Member
Looking for advice/ comments on a number of issues that have started to appear with my 300tdi engine that is fitted to a defender 90. It is the original engine with 166k miles on the clock.
Two issues have raised their head recently i do not know if they are connected but any thought would be welcomed on the potential causes

Issue 1 - The engine keeps running hot and heats up more that usual. for example after 30 miles on a dual carriageway/ motorway at 50mph the gauge starts shooting up. This also happens on longer climbs and it takes a while to cool back down or will not cool down unless i stop. Coolant was hanged less than 300 miles ago and the I have checked the radiator and clear it of any mud. I do not usually push the engine faster than 50mph as it seems happiest at this speed.

Issue 2 - After a long run the oil light will flicker when the engine is at idle however after slowing down and driving on local roads this issues stop after about 10-15 mins

Has anyone had similar issues together I have seen people with either issue but not in at the same time. Any advice on what I should be looking at as the root causes.
 
issue 1 check the thermostat is not sticking and make sure the fan is kicking in
issue 2 check oil level or make sure the bulb and earth is not faulty
 
Could also be an airlock in the cooling system from your coolant change causing the heat issues
 
raisingveg said:
issue 1 check the thermostat is not sticking and make sure the fan is kicking in
issue 2 check oil level or make sure the bulb and earth is not faulty
Click to expand...

300tdi doesnt have an electric fan.
Rad should be hot all over op needs to look at the oil cooler side of the rad also.
P gasket or head is next on the list, pressure test will rule out the head.
Air bubbles in the expansion tank is a good way to check.
 
If it is getting hot as you are driving at 50mph you can discount the fan at the minute, the stat/blocked rad/duff water pump would all warrant further investigation.
Has it still got the viscous fan fitted?
Is it losing any coolant? don't let coolant get low on a 300, they sulk if you do.

Oil light flickering is also a concern.
What oil has it got in it? mineral/synthetic, and what viscosity?

It could be that the engine is running so hot, the oil has become so thin it cannot maintain the oil pressure due to normal wear.
 
Thanks for all the information,
Still have the Viscous Fan fitted and there is no lose in coolant level.

Thermostat seems to be work correctly as the water is flowing though and into the rad when up to temp. Have check the Rad for cool spots but may take it off to give it a good flush or an new one to make sure.
Will also get it pressure tested to see if that point out any issues with the engine.
 
I had a RRC V8 and I overheated it and I had to do both heads. Everything was working fine but on inspection of the radiator the fins turned to dust. The core tubes were fine but it obviously could not loose the heat. It ended up having a new rad!

I have just taken the grill of my defender and that is similar, but I have not had an issue up to now. However, due to my experience with the V8 I think I will change it!!

The grill comes off easily so may be worth inspecting yours.
 
I did have similar fin rot [ sounds like we keep fish :D ] with my ninety, fine for normal driving but temp soon climbed when made to work. Swapped out then fine.
 
Check the condition of the radiator and, as mentioned, the P-gasket on the water pump. The age and mileage would suggest that one or both might benefit from replacement. My 300Tdi disco had both need replacing at a similar mileage. The radiator would show with the condition of the fins.
 
Knappster said:
Check the condition of the radiator and, as mentioned, the P-gasket on the water pump. The age and mileage would suggest that one or both might benefit from replacement. My 300Tdi disco had both need replacing at a similar mileage. The radiator would show with the condition of the fins.
Click to expand...

When you changed your radiator what type of replacement did you install (Steel, Aluminum) and what make. Interested to see if you updated at the same time and whether the upgraded radiators are worth the additional cost
 
I was going for a re core but local place had closed and so ended up with a Disco alloy plastic tank type from the flea bay. Been fine for a several years.
If by " upgraded " you mean greater cooling capability, then if you are not working it hard there is no reason to.
 
Have made sure there is no airlock in the system before I change the radiator thought I would check took this picture on the weekend. Most of the time the temp gauge sits bang on 12 but then will jump to the position shown in the photo below, would you consider this high or within the normal range.
PXL_20210612_113031135.MP.jpg
 
Have you considered a digital temperature gauge? I fancy fitting one.

I have heard that the 300tdi is susceptible to coolant loss and over heating. I have fitted a low coolant sensor so the temperature gauge seems the next logical step.
 
The red bit is hot..the rest is good. Youll never get a 300tdi hot unless your working it.
 
At your mileage, I'd be checking the injectors - they should have been serviced at 100K, and if worn, then the out of spec fuel spray pattern can cause overheating....

In terms of the gauge - and at its age, it might not be reading 100% - I would replace it with a Durite one - then you'll know the real temperature.
 
Capilliary gauge is the mutts nuts, dead accurate, works with no power.

To the op, I have noticed my 200 is running 5 degc hotter now the decent weather is here.
 
Disco1BFG said:
At your mileage, I'd be checking the injectors - they should have been serviced at 100K, and if worn, then the out of spec fuel spray pattern can cause overheating....

In terms of the gauge - and at its age, it might not be reading 100% - I would replace it with a Durite one - then you'll know the real temperature.
Click to expand...
+1 on getting the injectors serviced at that mileage. It's not cheap, but well worth it. My number 4 injector started going dickie at that mileage and caused that cylinder to overheat, melt the piston and wreck the engine. Injector service is cheaper!
 
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