Been nooging around a minor cold engine coolant loss for the last 4 years or so. Takes around 20 to 30 or so starts to loose a pint. Pretty sure the beast came with sealer jollop in the system when I got it as the problem only got noticeable after I pulled things out to fix the front crankshaft oil seal. Obviously fitted new hoses whilst the system was empty. Loads of Hermatite on the water pump and front cover gaskets suggesting that Bodgitt & Bend Garages Inc had been inside and given up. Water pump looked to be a decent quality replacement not original. Periodically one of the usual under bonnet leak suspects gets enthusiastic enough to leave visible traces and gets fixed after which the loss drops off for a while. No evidence of heater matrix O ring leaks.

So do I go (nearly) nuclear by doing the heater O rings and fitting new radiator, thermostat and water pump or do I just throw in the bottle of K-Seal I got given by a mate with a guilty conscience over too many little freebie jobs. Main temptation is that the K-Seal is free and quick! Being honest its only the heater O ring hassle that is putting me off the nearly nuclear option.

Car is a model year 2000 4.0 HSE with 88,000 on the clock.

Clive

Buy a couple of bottles of fluorescent dye for the coolant. I used this:
You can get a UV torch for a couple of pounds.
The advantage of the dye is that while small coolant leaks evaporate leaving no trace (well, eventually you might get some crystals), the dye remains and is easy to spot in a darkened garage.
IMO K Seal is a get you home in an emergency bodge, not a fix-all. Once in the system, it's a bu99er to clean out.

Thanks for that recommendation. Hit the buy it now button on a dye & torch deal. Should be here by the weekend and hopefully I'll see some evidence.

Know all about the difficulty of cleaning out K-seal and the other jollops.

Clive

Biggest problem with K Seal is that it clogs the bleed nipple from the top of the radiator so when coolant is lost and replaced with air, the air can't bleed out using the path that was put there for it.

The dye was instrumental in locating a tiny leak which didn't show under normal running as whatever fluid came out evaporated behind alternator/ aircon or on valley gasket.
Only knew I had a very minor leak somewhere after pressure/ vacuum testing cooling system...

Thats the sort of thing I expect to be looking for. Might be getting easier tho' as last couple of journeys its been loosing a bit more coolant. We shall see.

Clive

There are another couple of O ring joints on the system that are hard to see minor leakage from due to other stuff being in the way. Both O rings were fairly shot on mine:
Where the metal heater feed pipe fits into the inlet manifold
Where the metal outlet pipe from manifold to radiator top hose intersects manifold

Are they the same size as the ones in the heater matrix?

gordonjcp wrote:

Are they the same size as the ones in the heater matrix?

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I think the heater feed one is - ERR6434
Large one's an ERR7202

This was what the large one looked like. There is an O ring in there somewhere! Well in need of replacement.

Well thats turned out odd. Not used the UV stuff yet as leak has finally got big enough to see after running the engine during the air-con re-gas process. Appears to be coming from where the hose connects to the water pump inlet. Hose clip seemed tight but I've repositioned it and retightened it. Maybe that will have some effect.

Was surprised to get a steady stream of water out of the joint when the clip was loose. Sort of thing you'd expect if the hose is too large in diameter. Changed all the under bonnet hoses a couple of years back with OEM specification ones from a reputable supplier so should have been right size.

Clive