Overcooling? Where does your temp gauge sit?

[Ian21401]

Originally Posted by lnparry

Oh boy.

I'm afraid the special sockets with the internal spiral didn't work for me. I think the problem was that the hexagonal part of the nut on the thermostat housing is quite shallow in depth as there is a sort of oversized collar at the base. So, there was not enough of the nut to grab even when I tapped the socket home. Just spun off. The nut seems to be made of very soft material.

Further attempts with mole grips failed.

I wished I had quit then but in desperation I had a go with a mini grinding wheel on a Dremel. I've ground off a lot of the nut and tried chasing the rest around with a sharp screwdriver. No joy.

I don't think I have damaged the stud yet but quite ashamed of the mess I have made. So, as its getting dark and being cold, wet and generally p***** off have come inside to lick my wounds.

Not sure where to go now apart from shamefacedly hand it over to the local garage. Goodness knows how they will get it off.

Cheers,
LeeP

I know the feeling of having made a right mess of things and still not freed the damn thing. Cold wet and hungry doesn’t help either. Time for patience, step back and re-think. Surprised that the grip socket didn’t work.
Have you sorted it yet?

[Laird Scooby]

Originally Posted by Ian21401

I know the feeling of having made a right mess of things and still not freed the damn thing. Cold wet and hungry doesn’t help either. Time for patience, step back and re-think. Surprised that the grip socket didn’t work.
Have you sorted it yet?

I'm not surprised the grip socket didn't work Ian, it's a flange-nut, the flanks of the nut are much shallower than a normal nut so much less to grip onto.

Hence my suggestion of drilling the flange then drifting it round with a chisel.

That aside, any progress Jim?

[Ian21401]

Originally Posted by Laird Scooby

I'm not surprised the grip socket didn't work Ian, it's a flange-nut, the flanks of the nut are much shallower than a normal nut so much less to grip onto.

Hence my suggestion of drilling the flange then drifting it round with a chisel.

That aside, any progress Jim?

Point taken Dave but I’ve had a grip socket work on a 10mm head flange bolt. Maybe I was just lucky or the bolt head wasn’t too damaged.

While I’m here, my engine appears to have been overcooling lately, temp. gauge reading about 20% of the scale but heater output appears normal. First thoughts were stat.stuck open, or faulty sensor, or faulty gauge. Have bought replacement OE 92 stat but not fitted it yet. Tried spinning the viscous fan whilst engine cold. It would only free spin about 1/4 rev. I’ve previously been advised ( rightly or wrongly) that it should free spin about one or one and a quarter revs. when engine cold. ( and it has done so in the distant past.) So viscous clutch appears rather stiff. As weather is cold at present decided easiest first step was to remove the fan and see what happened. So, with fan removed the gauge now starts to move within about 5 mins of start up and gradually moves to around 40% or 45% of scale, as it used to and remains there. If having had engine stopped for a short while whilst parked, on initial restart the gauge reads about 55% then when car moving returns to about 40%. So it would seem that there is no problem with the radiator itself.
The above seems to rule out sensor or gauge faults and possibly even a faulty stat. Main culprit appears to be the viscous fan coupling not permitting the fan to free wheel when engine cold.
Not sure how to resolve this.

[Rversteeg]

The engine cannot be overcooling only because of a stuck visco fan clutch. Even if the fan is running all the time, the thermostat should be able to maintain a normal temperature by reducing the cooling water flow through the radiator.
Even if the visco clutch is working there is a constant air flow through the radiator when running at some speed. You will not see the engine temperature dropping under that condition either.
My first action would be to replace the thermostat.

[Laird Scooby]

Originally Posted by Ian21401

As weather is cold at present decided easiest first step was to remove the fan and see what happened. So, with fan removed the gauge now starts to move within about 5 mins of start up and gradually moves to around 40% or 45% of scale, as it used to and remains there. If having had engine stopped for a short while whilst parked, on initial restart the gauge reads about 55% then when car moving returns to about 40%. So it would seem that there is no problem with the radiator itself.
The above seems to rule out sensor or gauge faults and possibly even a faulty stat. Main culprit appears to be the viscous fan coupling not permitting the fan to free wheel when engine cold.
Not sure how to resolve this.

Remove the fan completely for now and fit a new 'stat Ian. Between now and when the weather warms up, consider fitting an electric cooling fan. The temp gauge should read about halfway so it sounds as if your 'stat is indeed weak.

[kelvinp]

Originally Posted by Rversteeg

The engine cannot be overcooling only because of a stuck visco fan clutch. Even if the fan is running all the time, the thermostat should be able to maintain a normal temperature by reducing the cooling water flow through the radiator.
Even if the visco clutch is working there is a constant air flow through the radiator when running at some speed. You will not see the engine temperature dropping under that condition either.
My first action would be to replace the thermostat.

The thermostat on mine was opening ok but not fully closing so it was obviously allowing water to continually circulate - around town the gauge would sit around the middle of the gauge, but on a fast run the gauge would drop back down due to the greater airflow through the radiator.

[lnparry]

Got lower nut off yesterday - only taken 4 days on and off!

Used a Dremel grinder and an old wood chisel to remove as much of the nut as I dared then needle files and finally sandpaper to get within a whisker of the thread on the stud. Finally cut down through the enlarged section at the base of the nut so I could get an open ended 8mm spanner on it and it finally shifted. Just not enough room to get a punch on it and hammer the nut. Moles and other grips just span off as Dave says.

Didn't have time to finish off so put a new plain nut and washer on so I can use the car for work and will swap out the thermostat at weekend. I know the other (top) nut comes on and off ok. Will report on temp gauge then.

What a pain. I'm sure someone more courageous could have had the nut off in half the time but I was just going a bit at a time as I was paranoid about damaging the thread on the stud.

Many thanks all for all the helpful suggestions and encouragement.

Cheers,
LeeP

[Laird Scooby]

Originally Posted by lnparry

Didn't have time to finish off so put a new plain nut and washer on so I can use the car for work and will swap out the thermostat at weekend. I know the other (top) nut comes on and off ok. Will report on temp gauge then.

What a pain. I'm sure someone more courageous could have had the nut off in half the time but I was just going a bit at a time as I was paranoid about damaging the thread on the stud.

You definitely took the right approach Lee!

Always better to take things slower with a back-up plan in place that you can use at a moments notice to keep the car rolling than go at it like a bull in a china shop and potentially cause yourself more work that you may not be able to do immediately for whatever reason.

At least you know that, come the weekend, you can whip the nuts off the 'stat housing with the new one ready to go in with the seal already fitted (or is it the more traditional gasket on the diesel?) so you can literally pop the old out, new in and get the nuts back on before you lose much (if any) coolant.

[Ian21401]

Well done Lee. Ditto what Dave said.

[lnparry]

ALL DONE!

New thermostat in and I have a nice vertical temperature gauge needle again. Pictures of the nut that caused all the trouble attached. Replacement thermostat 92 deg C which turned out to be the same temp as the faulty one that was in there.

One tip; I have a large syringe that a thin PVC tube can be fitted to (Dave recommended it for changing power steering fluid). The tube is small enough to pass into and along the outlet hose at the bottom of the expansion tank which goes to the rad. So I was able to drain water level to about half way down rad - took nearly 2 litres out. This meant that when I removed the thermostat housing all was nice and dry. You could also use the technique to swap out the top hose in the dry.

Now for that heater matrix - should be a doodle after the thermostat swap!

Cheers,
LeeP