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Getting hot!---200Tdi


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Lately my 90 200Tdi (disco 200) Has been getting hot when under load, at around 60mph she is fine creep to 65mph and the temp starts to rise over 80C and then at 70mph it gos up to 90+ It hasnt yet reached a 100C, To keep it cool I have my Twin electric fans running and the heater just to keep it under 90C, I thought maybe the coolant had got a bit diluted so ive renewed that and its been better but its still not right.

any suggestions?

Dave.

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I would try the simple things first.

Try changing the thermostat or remove it and do a drive test.

One indication of whether the radiator is to be blamed or the thermostat is faulty is try to figure out what has a more influence in reducing the coolant temperature: the electric fans or the heater?

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Is it suddenly getting hotter than it did? IIRC the thermostat only opens at 88oC so in theory it should get up to about 90oC when at speed... Also I suspect that the gauges are not that accurate... If there has been a sudden increase in temp at speed, then there is a problem, but I am surprised that the electric fans have any effect at 70mph...

As was said earlier - simple things first. I'd do something like this:

With the engine cold, examine the radiator for leaks evidenced by deposits of light green stuff (not critical to this investigation - but should be noted) or a core that is blocked with mud or has missing fins.

With the engine still cold. examine the main hoses - are they kinked, floppy-soft or do they have any other obvious defects - if so you will need to replace them. I have seen floppy hoses that have delaminated inside and were very constricted although they looked ok on the outside but they were very soft.. I've also seen hoses fitted so badly that they had a severe fold... (I've seen intercooler hoses fitted like this too, but that's another story)

Start the engine and have your assistant ( :rolleyes: ) run it at 2000rpm - examine the top hose again, this time for pressurisation (does it go hard? :ph34r: ) If so then suspect gasket or block or head problems.

Continue with the engine at 2000rpm and keep feeling the top hose - you are waiting for the thermostat to open when you will feel it suddenly go from nearly cold to too hot to touch in a couple of minutes. If it gets warm very slowly or not at all then suspect the thermostat or water pump or a blockage. (Thermostats stop working, water-pump impellers corrode to nothing and internal galleries get blocked with crud. If this happens you should drain and back-flush the system (do the radiator and the block separately), and remove and check/replace the thermostat (check it by gently heating it in a pan of water and watch for it opening), and then - if all else is ok - strip out and examine the water-pump...

Got to go to work now, but I think that covers what I would do for starters.

Good luck with it. Hope I haven't missed anything obvious.

ThreeSheds

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I would try the simple things first.

Try changing the thermostat or remove it and do a drive test.

One indication of whether the radiator is to be blamed or the thermostat is faulty is try to figure out what has a more influence in reducing the coolant temperature: the electric fans or the heater?

I would have said the heater has more effect than my fans do at the moment.

also what is the correct working temp?

I have a X-fan switch which cuts in at 88 and off at 83 for fan 1 and for fan 2 on at 92 off 87.

Dave.

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the fans arent there to keep the engine cool at 70mph, they're there to ensure there is sufficient flow thru the rad while driving slowly or stationary

you will most likely find that turning the fans off at 70mph will actually improve the airflow through the rad as the running fans will generate huge amounts of turbulence which disrupts the flow at high speeds

My moneys on the rad, it might be an idea to try flushing the rad before replacing it as they can fill up with carp!

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Whatever you do, do NOT remove the thermostat. This is because as the thermostat opens, it closes the by-pass. With no thermostat the coolant will circulate around the block and most will not go through the radiator.

If you don't believe me, RTFM which has a good description of how the cooling system works. Not that anybody ever reads it, of course.

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Whatever you do, do NOT remove the thermostat. This is because as the thermostat opens, it closes the by-pass. With no thermostat the coolant will circulate around the block and most will not go through the radiator.

If you don't believe me, RTFM which has a good description of how the cooling system works. Not that anybody ever reads it, of course.

Im assuming you mean dont drive without it.

Dave.

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The thermostat can be removed for a test drive, no problems. You shouldn't run without one on a regular basis, that's true, but that's another story.

Both 200tdi and 300tdi will happily run without the thermostat in the circuit. I ran my former 200tdi for 2 months in one summer without the 'stat 'cause I couldn't get a new one in my part of the world at that time. I ran my current 300tdi for about 10 days before getting a new one in place.

The bypass hose is much smaller than the rad hose. And its not the bypass hose diameter that counts but the 3 way connector (forgot the name) in which the flow is restricted to about 5mm.

The thermostat closes the bypass to maximize the flow through the radiator. Without the bypass closed you will not loose more than say 10-20% of cooling capacity, which is negligible for driving with 70mph.

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When the seal on my thermostat was perished (allowing all the fluid through all the time, effectivly the same as not having a thermostat in) I just found that I never got any heat and the heater never heated up. The fluid was constantly circulating around the rad and never had a chance to heat up. Then I put a new thermostat in and hey presto I had heat in the heater again.

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Is this a sudden change in temp or has it always done it? you comment you dont know the condition of the rad having not done the conversion i was just wondering if it was a new to you purchase and maybe the sender is wrong or something simple like that.

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sure this is probably very 'off the wall', but I'll pass it on anyway. A couple of cars ago I had a 200tdi fitted to a Range Rover Classic. I had similar symptoms to yourself - run along at a steady 60 and it was fine, start to go a bit faster and the temp gauge would rise and go off the scale. However if I stopped and restarted the engine the temp guage would be at 'normal'.

I figured it was something electrical and as I was 'living with it' the altrnator went on the blink and I changed that and a 'voltage regulator' behind the dash - if memory serves. After that, no problems at all.

As I say - probably completely irrelevant, but you never know.

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Lately my 90 200Tdi (disco 200) Has been getting hot when under load, at around 60mph she is fine creep to 65mph and the temp starts to rise over 80C and then at 70mph it gos up to 90+ It hasnt yet reached a 100C, To keep it cool I have my Twin electric fans running and the heater just to keep it under 90C, I thought maybe the coolant had got a bit diluted so ive renewed that and its been better but its still not right.

any suggestions?

Dave.

if it's a Discovery 200Tdi in a 90/110 then you need to use the Defender 200Tdi temp sender as the Disco one will not match/operate the temp gauge correctly. Defender sender is PRC8593.

as the others have mentioned, check the rad's lower rear face, on mine the lowest 4 rows of fins had rotted away & at high speed the temp rose & shoved the gauge upto the red sector.

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The Temp sender is fine, It hasnt always had these problems ive had the truck about a year now and only recently has it started doing this.

I will take a good look at the Rad tomorow and check the thermostat.

Bit off topic now but my Fans are mounted behind the rad+Cooler should they be sucking air through the rad via the grill or pushing the air towards the rad.

Thanks

Dave.

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Sucking fans on the back, or blowing fans on the front, in both cases pushing air through the radiator itself.

To inspect the radiator properly, you really need to remove it. More than likely the bottom 2" of fins will be corroded.

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well to be honest i hvae no idea as the conversion wasnt done by my self and im pritty sure it wasnt new, I was suspecting possibly the rad.

Dave.

CONVERSION wasnt done by my self just leaps out of the page!

Wrong radiator?

Wrong temp sender / gauge combination?

Then try the cleaning / changing / hair pulling :lol:

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I'd get the correct 90/110 temp gauge too. possibly borrow onr from a 90 or 110 owning mate, not the 300Tdi Defender gauge, needs to be the earlier vehicle gauge. works fine with the Defender 200Tdi sender & TD gauge in my 110.

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jcwcooper has said this is a 'new' problem, a while after the conversion work, so I don't think the gauge/sender pair is the problem - after all they're a matched pair - rather than a bodge.

It could be the 'stat, but i had exactly the same symptoms, and the radiator was obviously u/s when i took it out to replace it.

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