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Discussion Starter · #1 ·
2002 Disco II, here are the facts:
Head Gaskets, Timing Cover Gasket, and Water Pump all replaced 10,000 miles ago.

It overheated for the first time on a normal drive a few weeks ago after letting the engine warm up in the driveway. I turned it off, let it cool down and drove it back home.

I replaced the thermostat, which was old, and filled the coolant system until fluid streamed out of the bleed plug. At first start, the heat came on good and the engine warmed up to normal operating temperature in the driveway. As soon as I drove off, cold air blew from the vents and the temperature started to rise. I pulled over, let it cool again, and drove home.

The problem must be a loss of coolant flow, otherwise there would still be heat coming through the vents based on the water pathway through the system. The water pump doesn't leak or make any noise.

I want to flush the system next, what's the best way to do this? I was going to use a garden hose with a fitting to stick it in the engine water outlet hose and push in the opposite direction of normal flow.
 

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I know you don't want to hear this, but freezing in the cabin while overheating in the engine bay is a classic symptom of head gasket failure. If I were you I'd cut to the chase and do a cylinder leakage test first to confirm or eliminate that possibility.
 

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hmmmmm

Woooww... this is like deja vu.

I HAD heat in my rover, then a couple months ago it stopped. just when it was starting to get REALLY cold. (in VA) I noticed as did my wife that the heat seemed to be failing. I thought the thermostat. replaced it and the upper hose and flushed the system. The coolant that came out was horrid. Plus chunks or flakes... etc. I got everything sewn up and the heat still wouldn't work. We figured the heater core was it. Sure enough, after lots of "low pressure" attempts at flushing, I gave up and went radical. Mentally prepared to replaced the core, I went to a car wash and used the pressure washer.

SUCCESS!! I put everything back together, and also ended up replacing the core hose as well. now it's quite toasty.

Try flushing and consider that the radiator may be blocked up pretty well also. This in addition to the leak test in the engine.

Good luck and let us know what happened!

Macdad
 

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If the cooling system has been properly burped, then its possible excessive air build up is getting into the coolant from headgasket failure.

Also, an overheating engine without enough coolant in the system can certainly cause no heat because its not cycling enough coolant through the heater core.

IF there is indeed enough coolant, then you likely have the issue MacDad77 posted.
 

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Discussion Starter · #5 ·
Thanks for the advice.

Hopefully I'll get to doing a system flush with the garden hose this weekend. At least now that it's warm out I can test everything without constantly shelling out for coolant. There's definitely enough fluid in the system at the moment.

MacDad, how in the world did you hook up a pressure washer to your heater core?
I have one at home which I could use if this doesn't work.

I swear if it's a head gasket, I'm going to birth a kitten.
 

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Sometimes the thermostats are hard to open for the first time. Either take it out and boil it with a thermometer and see what temp it opens at or let it warm up then stop as soon or right when it starts going over. Sit at idle and see if the aux electric fans are working. If they are let it sit and idle and watch it. It should eventually open up and flow. The best way to do this task is take it out and boil it monitoring the temp.
When mine did this first off it never got over 3/4 on the gauge I stopped and did what I said, it stuck for a min at 3/4 or so and kinda lowered a bit then started cracking open . I think a pocket of steam gets tapped above or below it or might also be a pocket next to the sensor before it circulates or what ever. Also I used a 180° thermostat

Also how are you sure its not just still over heating and the thermo didnt fix it. Take it out and boil it to be sure.
 

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Discussion Starter · #12 ·
I can try the boil test on the thermostat to confirm it's working properly.

The symptoms point towards some kind of a vapor lock or a clog that's what I'm thinking.
 

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Discussion Starter · #13 ·
Flushed the system. No chunks, very clean indeed.

Refilled and had the same issue. I've come to a conclusion though.

I've ordered a new water pump. This one must just have worn out. I didn't want to believe it because it has only 10 grand miles on it but it makes sense. The heat would work when the engine first started because the thermostat was closed so all the circulation produced by the pump would be routed through the heater core. As soon as the thermostat opened, the water pump would not be able to make enough flow to push water through the radiator and the heater. It would move just enough water to keep the engine from overheating while idling but as soon as there was load on the engine, it couldn't keep up.

I bought the genuine water pump this time...
 

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Discussion Starter · #14 ·
:complain::complain::complain::complain::complain::complain:

Installed the new water pump tonight. Flushed the block with the pump out while it was open. Installed a new upper radiator hose and bleed valve. No Luck!!!!

Exact same symptoms. Runs fine, heat works great while warming up then shortly after it hits operating temperature the heat cuts out and the temperature starts to rise. I'm completely stumped... :help

I'm running out of plan B's
 

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Discussion Starter · #17 ·
Hydrocarbons in the coolant... did the head gasket leak test with the blue fluid which turns yellow with the presence of exhaust gases to confirm this. Truck is done it seems.
 

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Hydrocarbons in the coolant... did the head gasket leak test with the blue fluid which turns yellow with the presence of exhaust gases to confirm this. Truck is done it seems.
Sorry to hear that but it was my suspicion all along. I wouldn't say the truck is finished. You could do the head gaskets again and try and figure out where you went wrong, or you could look for a good used engine. You do have options.

Have you retorqued the heads? Hell, if you really think it's sayonara, put some Bars Leak in it. If it's a small enough leak, you could get lucky. What do you have to lose?

If it were me, I'd probably be rolling up my sleeves to get started. I'd have to know where I went wrong the first time.
 

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Discussion Starter · #19 ·
I'm going to throw some blue devil head gasket sealant in there to see if I can run her though the summer but the windshields cracked and there's no response from the ECU with my OBDII scanner so it won't pass inspection. The trucks already on a salvage title and I have too many projects and not enough time to deal with it. Hopefully I can tow the boat one last time with her after that she will be missed. On to another one I suppose.
 
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