rover 25 diesel overheating on motorway

[BillyJohnLee]

picked up my new 25 diesel yesterday, but as soon as i got on the motorway the temp rose, put heaters on full and they were cold, and it overheated. the rad felt cold, but the water was boiling

i let it cool, filled it up and carried on. repeat twice.

then we got onto single carigeway stuck behind a lorry and it cooled a bit, it was still to hot, but drivable at 50mph/2krpm

anyone got any ideas? thermostat? water pump? Headgasket?

[Popeye 89]

possible head gasket or cracked head fella, was it from a dealer?

[Rik420SDi]

Worth checking to see if it's circulating water - pop the coolent return off the header tank (engine cool, obv.) and see if water is flowing, give the throttle a blip and the flow rate will increase. Absence of flow or increase of flow on revving would indicate coolent pump problems.

Any steam or coolent-smell from header tank or exhaust? Coolent hoses getting pressurised very hard soon after starting?

Water pump piggybacks off the PAS pump by the way, not cambelt driven on the diesel engines. If you do need a pump there are excellent pattern-parts on ebay for £20 - top quality too.

[Enright]

Could be sheared water-pump drive after the Winter weather.
The water pump is driven off the back of the PAS pump. If insufficient anti-freeze is used and there's a big freeze, when you try to start the car it can shear the locating dogs off one or both of the spindles.
You end up with localised boiling and no circulation, which WILL result in head-gasket failure if not sorted.
To test for it, find the hose that goes into the centre of the water pump (it's about half way down the engine under the intercooler pipes).
Pop the pipe off and see if you can spin the water-pump's impeller. If you can, then you may need a replacement water-pump or a PAS pump. Unfortunately here's no way of finding out which one has been broken until you get one or the other off, as they join end to end.
If the pump's impeller is solid (as it should be) then my next port of call would be thermostat, but it's an absolute swine to get to - the front cross-member has to come off.

Good luck.

BCingU,
En. ;-)

[BillyJohnLee]

Cheers guys. Iv checked the water pump and that seems fine. Stat was next.

The top hose was boiling but bottom stone cold. This would point to thermostat wouldnt it?

Im hoping it isnt the headgasket. But icam prepared for that.

Good job it is tidy and it was cheap.

[BillyJohnLee]

Is there an easy way to check if it is head gasket?

[Enright]

Yep, sounds like a stuck stat to me.
Nice cheap fix - result!

BCingU,
En. ;-)

[Popeye 89]

surely a stuck thermostat wouldnt stop heaters getting hot?

only reason i said head/head gasket is because ive been and seen one with exactly these symptoms.

by all means, check for the cheaper things first though

[pervavore]

I would change the water pump and thermostat. How have you checked the water pump?

[BillyJohnLee]

Popeye, yeah deep down i think it is the head gasket, but im hoping its not and checking other stuff, im always the optimist

i took the cover off the water pump, it all looked fine and it wouldnt move, so i turned the engine over and it span.

[Enright]

If a thermostat isn't immediately available, can't you just leave it out of the system for a few days to see how it goes?
Obviously I wouldn't suggest doing this long term, but for fault-finding it might help.

BCingU,
En. ;-)

[pervavore]

But if form the heater warm air isn't coming out than the thermostat isn't faulty.

[Chrisund123]

Water circulates through the heater when the 'stat is closed, so I doubt it's a closed 'stat.

My money is on a sheared water pump, quite common if the water has been allowed to freeze.

Is there any problems with the power steering? as the coolant pump "piggy backs" of off the power steering pump. I reckon the drive from the PAS pump to the water pump has broken somehow. How did you check the water pump?

[BillyJohnLee]

Originally Posted by Chrisund123

Water circulates through the heater when the 'stat is closed, so I doubt it's a closed 'stat.

My money is on a sheared water pump, quite common if the water has been allowed to freeze.

Is there any problems with the power steering? as the coolant pump "piggy backs" of off the power steering pump. I reckon the drive from the PAS pump to the water pump has broken somehow. How did you check the water pump?

i took the cover off the water pump, it all looked fine and it wouldnt move, so i turned the engine over and it span.

my thinking was that if the water was boiling the stat would be open and the radiator and bottom hose would be hot?

[Rik420SDi]

Heater cold all the time could also be a knackered gate valve or blocked heater matrix. I had both on my 200, infact the heat output was always poor even when the system was flushed twice in the space of a fortnight to get rid of the muddy and murky nature...

[BillyJohnLee]

Cheers guys. Its defo the headgasket (pressure in coolant tank after reving from cold)

Any tips for doing it? It wont be the first iv done but the first diesel.

Can i use drill bits to lock off the pump? How likely is it i will need headstuds?

[Rik420SDi]

There have been some reports of heads cracking, just so's you are aware - would be adviseable to get the head pressure tested. Other than that it's a pretty straightforward procedure by all accounts. Also a good time to replace the belts and tensioners etc - I can vouch for THIS KIT, the cheapest I have seen anywhere and good quality. I got one for my 45

There are others better qualified than me to advise - but yeah you can use drillbits, it's 6.5 for the crankshaft and 9mm (I think) for the fuel pump. I've no idea on the head bolts, but personally (for the cost involved) I'd be tempted to get newuns.

[BillyJohnLee]

Cheers for all your help guys.

this is the outcome so far..the Problem.



Back of the engine between 2 and 3? i assume that is where it went?

[Bunny_Brain]

Looks pretty bad does that. You can see the path to the water jacket as well. You can reuse the head studs but I would suspect the head will be recessed where the fire rings have failed so a skim may be worth while.

[zr-td-nutters]

i would say 2,3 and 4 by the looks of it but this is good news if the hg is clearly failed normally means the head is not cracked but i would at least skim it also i would check things like if the turbo has been buggered around with and make sure the rad is clear as hg failing like this is very very rare and only times i have ever seen it is when i tuned a derv a little to much with the std turbo.