Tracing a coolant leak

[gargravarr]

Hey all,

Just when I thought I'd fixed the Black Beast, I get a phone call from my mum in France saying the truck's overheated again. Last time, we traced it to the water pump leaking, which after a record amount of swearing I replaced and sealed properly.

I've been keeping an eye on the engine, and despite being pushed occasionally the machine stayed cool, so I thought the cooling system was sound, but it seems there's a leak somewhere. I've been seeing moisture with a green tinge (i.e. coolant) on the side of the engine underneath the fuel injectors. The entire engine block has been covered in this moisture every time I look, so I can't see where it could be leaking from. Yeah, this sounds like poor maintenance on my part, which it could well be, but we gave the truck to a mechanic to look for the leak and he couldn't find anything out of line - all hoses etc fine and sealed.

Given this, how would I go about tracing this troublesome leak? It seems to be a tiny one, only opening up when the engine's hot and the cooling system's under pressure, i.e. a long motorway drive. And naturally, at that speed I'm guessing the leaking coolant is being plastered all over the engine block. I can fully appreciate coolant being coloured to say 'this ain't water here, you've got a leak!' but at the moment, all it's saying is 'on the passenger side of the engine.' I don't know a lot about the 2L-TE, but the only cooling system component I'm aware of on this side is the filler/distributor, and that got a clean bill of health from the mechanic. Any ideas where I could start?

Sorry to ask for so much help for this machine, I really am, but I'm starting to feel out of my depth with this car

Cheers,
Gargravarr

Edit: should also add that I put Radweld into the system before we twigged it was the water pump, so that appears to have done zilch.

[TonyN]

There are two hoses that go from by the filler neck to the intake manifold, also the short hose connections under the filler often leak.

THere are also core plugs around there.

If its that much, when you pull up after a motorway run you should be able to see where its coming from.

[Albannach]

Could be the rear heater pipes too, or the overflow pipe?

[shokenore]

You may well want to have a look at the actual rad cap seal,sometimes they leak from there,probably only a weep but it ain't gonna' refill itself .

I "pressurized" my system with a bike pump took one or two pumps with the block cold ,it helps if you have a pressure gauge on the pump to make sure you are not going too high a pressure.I found all the original hose clamps were weeping ,changed them all and no more weeps.

[gargravarr]

You may well want to have a look at the actual rad cap seal,sometimes they leak from there,probably only a weep but it ain't gonna' refill itself .

I "pressurized" my system with a bike pump took one or two pumps with the block cold ,it helps if you have a pressure gauge on the pump to make sure you are not going too high a pressure.I found all the original hose clamps were weeping ,changed them all and no more weeps.

Now that ain't a bad idea, I was wondering how to bring the pressure up in the engine without running the thing full-throttle, never thought of using compressed air. What did you do, attach the pump to the expansion-tank hose?

As to Tony and Albannach's advice, I'll forward this on to my mum and see if she can get something done about it. She's supposed to be out in France for three weeks and hasn't even been there three days and the car's dying on her!

[shokenore]

I used the rubber bung off a old bottle of Infacol (colic medicine from when the kids were babies)

But I guess a stopper off a home brew demi john would be ok or something similar.

I took the pump adaptor hose and squished it down the bung hole and squished the bung down the rad cap filler hole gave it a couple of pumps and you could see all the coolant weeping out from the hose ends.

[NiftyNev]

I made this before I had a proper tester.



Just connects to expansion tank hose. Just be sure seal in radiator cap is ok.

Nev

[Rob5464]

I have an air compressor and was going to use that to pressure test my system. I have a bad leak somewhere but can't find it even after giving it a hard drive.

If I drive with a lead foot on the motorway, I can drain the water enough to cause the temperature to shoot up in under 10 minutes. I changed the radiator cap but it didn't do anything.

I have lost a lot of pressure as I can remove the rad cap when hot, with my bare hand fairly easily. Correct me if I am wrong but if the head was gone it would be over pressurised not under.

Anyway enough blabbing; what I was meaning to ask was how much pressure should I use? My compressor goes to at least 175psi But I don't fancy ramming that down my top hose.

[NiftyNev]

About 15 PSI maybe a little higher if leak is hard to find.

Nev

[shokenore]

I made this before I had a proper tester.



Just connects to expansion tank hose. Just be sure seal in radiator cap is ok.

Nev

Like that !!much better than the gauge on my push bike pump.

[Rob5464]

About 15 PSI maybe a little higher if leak is hard to find.

Nev

I would have expected higher than that but I will give it ago.

I too used some radweld, it greatly reduced the leak but it didn't last. I was hoping it would help me find the leak but it didn't.