2.5V6 coolant and fan woes

[Forestgreen]

Hmmm, if I flush out the sealant so I can have a new working heater matrix my leak will recur. If I don't I'll freeze to death driving to work in the winter. It sounds like I've had a run of bad luck with this engine and time to move on and fit another. Yes I know it would be cheaper to buy a new car (maybe.....there's a low mileage V6 on Autotrader at the moment for £9995) but the car is otherwise in sufficiently good shape, and I've spent a lot to keep her going so I want to be able to continue enjoying her for a while.

[TomRS]

Glad your taking the plunge and keeping her road going, engine out job isnt really all that hard just takes a bit of time.
Once its all done you'll know you've got a gooden, and replacing all the bits with the engine out is a lot easier!

[zefrench]

Originally Posted by Forestgreen

Hmmm, if I flush out the sealant so I can have a new working heater matrix my leak will recur. If I don't I'll freeze to death driving to work in the winter. It sounds like I've had a run of bad luck with this engine and time to move on and fit another. Yes I know it would be cheaper to buy a new car (maybe.....there's a low mileage V6 on Autotrader at the moment for £9995) but the car is otherwise in sufficiently good shape, and I've spent a lot to keep her going so I want to be able to continue enjoying her for a while.

If the sealant did its job, why not flush it ? The only way the leak stopped if the sealant dos the job is that Sodium silicate turn solid. This you don't need any of what is left of it in the cooling system.

Did you have to remove the thermostat ?

[Forestgreen]

A month on I thought I'd post an update.

I took the car along to the nanomeet and there was plenty of prodding and poking but a general concensus that there wasn't any evidence of pressurisation, all the rubber tubes were soft and spongy etc. The bottom hose was stone cold however. ANd the T4 confirmed that whilst the fan came on at both "low" and "high" triggers, in both cases it spun at "high" speed.

Not sure what the prodding did but on the way home the engine shot up to 120 degrees so I had to pull over and wait a while before checking coolant levels. To my surprise the coolant levels in the expansion tank were fine, but there were large solid gunky things floating around which were presumably blocking up the system. I continued the rest of the wsay home at a leisurely 20 miles an hour so as to keep the engine as slose to 100 degrees as possible and took the car back to the garage that had added the steel seal the next day. They flushed the coolant and remaining steel seal out, using white vinegar initially as advised by the manufacturer to break up any clots. Coolant levels remained fine after that, but the heater matrix still ran totally cold.

Last weekend Terry fitted a Revotec fan and changed the heater matrix, thus once again draining and exchanging the coolant. This is what came out of the old matrix:



Unfortunately after putting the bumper back there was still no heat coming from the matrix so it was bumper off again and we bypassed the oil cooler. This time result! Blistering hot air coming out of the heater wents on both sides when climate control was on maximum.

For good measure we also changed the rear numberplate circuitboard for a brand new one from DMGRS as the bulbs were doing their Christmas lights display of working intermittently.

Checked the levels yesterday, oh dear. I had to top up with around 500 mls. I took the car out for a spin and in the course of the ride the new rear numberplate bulbs both went out.

This morning coolant had gone down a bit though not as much as yesterday, and one of the numberplate bulbs decided to come on.

So apart from the "new" issue of whether the new circuitboard is faulty, are we back to square one with the coolant leak again? Or should I expect to have to top up a bit for the first few days after working on the coolant system?

For good measure earlier in the week I fitted a new tyre and had the suspension top mounts changed and tracking adjusted so the car runs beautifully. However, the car is no use to me if I can't go far without having to top up with coolant and if this persists I will have option but to sell. The past four weekends have been spent at various garages and other places and with a family and a busy job that requires a reliable car I cannot afford any more time off to investigate problems so unless the coolant holds, I will be selling soon.

[SD1too]

Thanks for the update David.

Originally Posted by Forestgreen

The bottom hose was stone cold however.

That was a huge clue.

... there were large solid gunky things floating around which were presumably blocking up the system.

Yep; the Steel Seal which your garage put in.

... we bypassed the oil cooler. This time result! Blistering hot air coming out of the heater ..

Oil cooler blocked with Steel Seal. That's why your bottom radiator hose was cold. It should feel hot.

Or should I expect to have to top up a bit for the first few days after working on the coolant system?

Yes! I hope that the MGR refilling and bleeding procedure was followed. I have added a note at the end concerning topping-up the system for a few days. Here it is again. Please read it and act upon it! Golden rules David as follows:

• Don't add any sealant product to your cooling system.
• Follow the MGR refilling and bleeding procedure exactly.

Simon

[Forestgreen]

THought I'd give an update after a couple of years of topups. My 2.5 has had a persistent slow leak over that time (typically about 1ml per mile) and I've been topping up with half a litre of coolant every 500 miles or so. When I remove the coolant filler cap I get a slight whoosh of pressure, and a test found combustion gases in the coolant. So I've been thinking dropped liners or head gasket. Pressure test failed to find any leak and thermostat is clean (but not working - another story).

When the leak first manifested it was loosing me around 5ml per mile which wasn't sustainable. A local garage chucked some Steel Seal in (which we had to drain out a few days later as the engine began overheating despite the coolant tank staying full). It left me with a blocked heater matrix (since replaced) and a thermostat which is stuck open, meaning that for the past two years/12,000 miles I've been driving around with an engine that barely rises above 70 degrees C. Economy doesn't seem noticeably worse however, and the leak is just about manageable.

I had to drive 450 miles in one day last weekend (three lots of 150 miles with two breaks each lasting a couple of hours so the engine stayed fairly warm), on a really hot day. Before setting off I topped the coolant to halfway up the fins (so more than maximum). Next day with a completely cold engine the coolant level had dropped....by less than a centimeter, so still above the maximum level! And there was no "hissing" when I removed the filler cap.

Does that give any further ideas about why I get the coolant loss and what I should do (other than keep going, and check the fluids every couple of weeks)? In a nutshell, when commuting/city driving which is around 10 miles each way, I'm losing around 1ml a mile. Yet if I do an extended run I lose nearly nothing. Evidently the coolant is being lost whilst the engine is heating up.

I guess at some point I should replace the thermostat - the main problem with a permanently open thermostat is that the cabin heater is less effective at warming the cabin in winter. I am toying with opening up the engine and replacing the head gasket in case that's the source of the leak - but we are talking £££. I haven't discounted first trying a bit more Steel Seal to see if I can nail the leak once and for all (though I realise I might block the heater matrix again and no point doing it after adding a new thermostat in case it sticks that again too).

Can anyone suggest why I get significant coolant leak in city traffic, but a much slower leak on long motorway runs?

[kaiser]

The engine would tend to run slightly hotter in town. Then also higher pressure, and with any leak, higher flow through the leak.

It sounds like a plastic crack opening with pressure or maybe a seal on the water pump, leaking at higher pressures.

This might not be what is happening, but it can explain what you see.

One test is to leave A/C on in town to make sure the engine gets max cooling, and see if that lessens the water loss.

With a small loss like this, it can easily be an outside leak that evaporates before you can see it.

Stationary running on a piece of cardboard might reveal something. Switch fan off and observe temperature on the screen.

[SD1too]

Originally Posted by Forestgreen

Can anyone suggest why I get significant coolant leak in city traffic, but a much slower leak on long motorway runs?

I had something similar David, until I fitted new seals to the expansion tank cap. It’s also very important to refill and bleed the system according to MG Rover’s procedure.

Simon

[Forestgreen]

Yes but we did all that when the leak first manifested - two new filler caps didn't fix the leak, pressure test was OK, colour change for combustion gases in coolant (and on flooring the throttle you could see gas bubbling up out of the expansion tank) and adding Steelseal made the leak much slower but still present.


What I have established is that in daily city commuting of 10 miles each way I am getting through 500mls of coolant every 500 miles. In a nearly 500 mile continuous drive with only a couple of breaks short enough for the engine to remain hot, coolant drops by only a small amount.


The engine never gets above 80oC even on a long run as the thermostuck is stuck right open.


So, where's the leak likely to be and what would be best to fix it? Or should I live with it?

[Skilrove]

So gas bubbles through when you apply heavy throttle? Surely that is now a clear diagnosis of HGF? Have you been able to confirm or otherwise make progress since last posting?