Car radiator leaking – is that repair fluid to put in worth a go?

My car is loosing coolant, only slowly. Is it worth putting some kind of repair fluid in the radiator to try and plug the leak or is that just a worthless gimick?

If it is worth doing, which brands are ok and which should I avoid?

I’ve used it in the past but only on old cars, it works but not sure if it has implications for your water pump etc.

What type of car is it? Age?

Check your hoses for splits as well as it may be that.

It might be worthwhile looking for headgasket symptoms…HOWEVER need alot more info first!

If it’s an old car you don’t care about dump it in. Radweld should sort it.

If it’s a new car you care about. Get it fixed properly.

Its a very old high milage japanese car. It is leeking oil from somewhere too very slowly and has less acceleration, which oculd be the high milage. I am wondering if it is a head gasket problem myself, but I have not really got out and had a good look round. I dont think my garage will be keen to repair it if so, as they will probabally suggest scrapping it instead, due to costs. Hence hoping the 2 leaks are not connected and that the water is going out in another area. Wishful thinking I expect, but not really in position to replace the car. If by good fortune it is the radiator (not with my luck), I am still wondering if the repair fluids are worth a shot if the leak is small. I think it is loosing about a pint a month, with plenty of milage.

radweld will possibly do the trick, and is possibly your best chance. my experience is that it’s only a temporary measure though, and if there is a leak in the rad, it’s more than likely the rad will need replacing in the not too distant future. if the leak is elsewhere, check everything! if it’s the start of a crack in a pipe (plastic especially) then it could fail spectaularly… resulting in a sudden loss of all coolant, and overheating & subsequent seizing of the engine. happened on my sisters car, and needed best part of 1300 quid to pull engine apart, bore the cylinders to remove splatters of molten piston, replacement of all the pistons and other gubbins and skimming of the cylinder head….

Pint a month? Has this happened recently in the cold weather? Cars use alot more coolant in winter/cold weather (thats if its disapearing). If its dripping out then Radweld and bin later on.

To be honest, I dont really know when it started, I was doing a bits and pieces check on it around a month ago and noticed the coolant reserve tank had emptied, so I topped it up. Checked it again last night and most of it had gone again. I realise from this I am going to have to keep much more of an eye on it.

I broke down in an overheated car once (not mine) and fortunatly it just seized up and ground to a halt. Amazingly there seemed to be no long term damage to his car. Twas due to oil loss I think (long time back to remember).

I would have thought that it is more likely to be a hose joint than anything else.
Can you not see any wet areas on the ground when you go out to the car first thing? My girlfriends car was losing loads of coolant but there was never any on the floor and it turned out to be the gasket around the thermostat. It was only coming out when getting hot and was then evaporating away.

I’d start by looking for splits in hoses/perished hoses, particularly around the ends.

Midnighthour sounds like cold weather then to me. I’d just visual it everytime you fill up with petrol and keep running. If its only a pint a month and its a snotter then you’ve nowt to lose if it isnt the coldweather.

Thanks guys, I will go out an have a decent look. Thanks for hints and tips where to start.

(I have not noticed anything on the floor, but then it must be loosing stuff quite slowly so may not be making a notiable puddle, it sits on a driveway so the surface is damp often anyway.)

It is leeking oil from somewhere too very slowly and has less acceleration

Sounds more like a head gasket problem to me. Losing water, oil and down on power, very symptomatic of a HG leak. Any mayo in the water/oil filling areas?

Pint a month? Has this happened recently in the cold weather? Cars use alot more coolant in winter/cold weather (thats if its disapearing). If its dripping out then Radweld and bin later on.

Cars shouldnt use ANY coolant, its not a consumable, its a sealed system. If you are losing ANY water at all on a modern (85+) car you have either a leak or worse. The level in the expansion tank may fluctuate, but should never need topping up.

I agree with coffeeking. sounds like a head gasket issue

If you can get the cap off the radiator…………….

Check to see if there’s any oil contamination in the water. If there is = head gasket.

Then with the engine running, operate the throttle. If you can see air bubbling up. The head gasket is foobared and venting into the cooling system.

If it’s an old car with loads of miles, and you don’t normally cane it, it’s more likely to be something simple. As others have said. Look for the easy stuff like split hoses etc first.

Good luck.

Look for the easy stuff like split hoses etc first

I’d eliminate the mayo in the oil/water first, save checking hoses 🙂

Additives can also block your heater matrix too. Worth checking on Fleabay for aftermarket radiators, often huuuuge savings over factory replacement. Usually straightforward to swap DIY

There’s another product that’s a bit better than radweld. Costs ~£14 per bottle. Will ask a colleague what it’s called & report back later.

I know someone with a carina who went through 5 bottles of radweld, 2 eggs and 4 litres of oil in 6 months before deciding to scrap it. Radiator and heater matrix still wasnt blocked amazingly – the thing about radweld is that it should remain liquid until its in contact with air (i.e. at the leak) – hence I’ve never seen it block anything unless the leak wasnt cured (and so air continued to be present in the system.

Yeah there is something recommended by my garage, it is a lot dearer (just under £20 I think) but supposed to be much better for not blocking your system.

I last used Bars, it was like an oxo cube that you crumble into the expansion tank. Worked for months on my Laguna up until I got rid of it.

I’d try Bars before Radweld for sure, only cost about £2 too.

coffeeking and stratobiker. I’ve recently had to ‘burp’ the coolant system on my car due to the garage not remembering to tighten up the hose leading into the radiator (hence the radiator emptied upto 2lts of coolant over the engine). Part of the burping process involves starting the engine and holding slight revs to get the level of coolant to overflow from the radiator cap (tie rag around to collect overflow)- if it bubbles yes its fubarred, it should just seep out/overflow. Then top up and recap. I’ve also found out by cross-referencing technicians that coolant can drop in extreme (cold) weather. So there! 😀

Look for the easy stuff like split hoses etc first]

I’d eliminate the mayo in the oil/water first, save checking hoses [:)]

Good Point 🙂

Are you brimming the radiator each time you refill? The car may ‘appear’ to loose coolant as a certain amount will overflow when the water pump is running and coolant is hot. For my old Citroen, a pint or two of water sounds about right for this, it would always drop to a certain level soon after refilling.

The first car I had would leak coolant on full lock as the steering rack moved a rubber hose, opening up a crack.

everytime you fill up with petrol and keep running

hora your a mong!! how leithal are you!!!!