Car radiator leak

In message snipped-for-privacy@4ax.com, Chris Hogg snipped-for-privacy@privacy.net writes

WHY? Self-amalgamating tape might be better.

As you know, the problem is that the thermostat probably wants to run the water above 100C. To keep it down, it might help to turn the heating on, and set it at full blast.

Old cars were very forgiving this way, we had a similar issue on an old Hillman Minx back in the 60s. You need to keep a very close eye on the temp though, not sure what a diesel is like though. Brian

Put an egg in the radiator? Brian

Water passages are narrower on modern cars, so more inclined to block, so an egg (or any sealant) would not be a good idea.

Most diesels tend to take a long time to warm up, don't need much cooling, yet many have the default petrol radiator fitted. So it's unlikely to create much pressure.

Depending on how big a leak, you might get away with it, but get it fixed as a priority.

I was also going to suggest self-amalgamating tape. Duct tape will lose adhesion when wet.

I'd be more inclined to try a sealant, Barr's was always my favourite.

Doesn't sound like a split hose, that would be what we call in the trade a revealed fault in that with the radiator topped up and engine warmed up to running temperature / pressure it would be very obvious, and losing coolant at an unacceptable rate. I would not expect it to be practicable to "bodge" unless the hose is very accessible.

As others have said, diesels don't warm up particularly quickly and 10 miles is not very far, but probably far enough to get up to temperature.

You could try cap off and bottle of water, but I'd expect to see boiling at that distance.

In article snipped-for-privacy@4ax.com, Chris Hogg snipped-for-privacy@privacy.net writes

Bit of rigorous pulling should reveal a split or perished hose. But do you want to gamble on blowing your engine for the inconvenience. Diesels are very unforgiving of temperature overheat.

But the odds are on what I would call a modern car is that the hose is inaccessible and the leak non-obvious. I'd be inclined to top up, put the cap on, let it warm up on the drive, and see if you can spot the leak.

I have not had a hose fail for decades, they are made from better stuff than when I was a lad. My guess at 15 years is that it could be a corroded core plug. And I still think that a (proper) sealant is the obvious first fix (might prove to be permanent). I have not used one for ages, I guess these days there might be different types depending on the materials or coolants.

And I completely agree about diesels being unforgiving of overheating.

Good way to ruin things like the heater, IMHO.

Is there another sort of overheat? :-)

In this case it's about balance of risks, though. I was mostly using Barrs in the old days when perhaps clearances were larger, but it contained fibrous lumps that seemed to work, and (on the three or four occasions I used it) didn't have any problem. Holts did a white milky stuff without "bits", I never quite trusted that.

While there is only a small risk of serious overheating if the OP "drives carefully" I don't think it is zero. I agree, the risk of heater blockage is not zero either.

Having used Holts' Radweld, you then needed Holts' Radflush and so on ....

Take some water with you and just drive it. Don't mess around trying to seal it. Keep an eye on the temp gauge. If it is higher or lower than normal stop and have a look. Don't take the cap off while the engine's hot unless you cover it with a cloth.

Bill

economic overheating?

Bill

Thanks for all the replies. I've just topped up the radiator, and let the engine idle for about 90 minutes so that it got up to full temperature and probably opened the thermostat. A few drops of water appeared early on, but nothing very serious, so I'm thinking I was being overly pessimistic. It should at least allow me to use it for the next few days with caution and a container of water in the boot. As others have suggested, it might not be that easy to see where the leak is coming from anyway.

Many years ago I used Radweld on my first car - a little MG TC. But there was a small square hole through one of the core-plugs, looking as if a previous owner had knocked a nail through it. Radweld sorted it out. But I hear the caveats of using a leak-sealant on modern engines.

If you have a UV lamp then UV dye for coolant doesn't cost a lot and can usually show where the water is /going/ if not precisely where it's coming from.

Thanks. Yes, I have a UV lamp, so that's a useful tip. I'll Google for dye.

As a man with a UV lamp you may well know this already but just in case......it's worth using the lamp to look around *before* you run the engine with the dye in case you need first to map all the places which show where someone's used the same colour before you.

But if overheating the limp home mode will probably trigger.