Test for HG failure or EGR cooler? Coolant leak.

Fern30 · **Posted:** Mon Apr 04, 2016 8:33 am

Heres the mesh and the tape holding the edge of the lower pipe mesh in place. Don't think its a repair just to 'neaten' the edge of the mesh and keep it in situ. But the tape was all aglow! Could be leaking from the crimp joint or just a pinhole in the rubber. On a night shift tonight so will have a look after the drive in. See if i can get any pictures of the uv glow.

papaindigo · **Posted:** Mon Apr 04, 2016 11:35 am

Ok it's a 2.5L Cherokee, 2004 or earlier, and you are in England so it's right hand drive so your setup is different from the US 05/06 left hand drive 2.8L models. The picture suggests the coolant flow routing to the heater core is across the top of the engine from the viscous heater and then to the heater core which is on the right side of the firewall when viewed from the front (it's on the left for the 05/06 US models). Yes the 05 FSM (http://colorado4wheel.com/manuals/Jeep/KJ/) confirms flow to the heater core at all times. My guess is the heater hoses are shot and leaking a fair amount of fluid on the engine where it dries from engine heat hence no puddle on the ground.

What is a bit odd (e.g. different from 05/06) is the crimped metal to heater hose connection. I suspect a dealer will want to sell you a rather expensive combined metal pipe/rubber hose OEM replacement. However you should be able to get by with just heater hose and some new (don't reuse OEM spring clamps) clamps. The heater core end should be a simple hose clamp based on the FSM image of the heater core. For the rest of the routing you can either 1) replace the metal pipe/rubber hose entirely with just hose being careful that there are no problem rub points in the routing or 2) cut the crimp end off the metal pipe and secure a replacement rubber hose with 2 clamps. I say 2 clamps because a normal metal pipe to be connected to a rubber hose will have a "flair" at the end to ensure a good seal; since you will cut the pipe its end will be straight so best double up on the clamps to be sure the joint won't leak.

Yes as I noted in my initial post you have to be in shade or a dark area to look for the UV dye as it's not at all bright.

Mountainman · **Posted:** Mon Apr 04, 2016 12:34 pm

I would think that if it's leaking that fast, that you would be able to see it at elevated idle. I'd try watching for steam with someone in the cab holding the RPM's to about 2k on a warm engine for a couple of minutes. Also, I'd stare at the tail pipe under the same RPM's. That's a lot of fluid loss :shock:

Fern30 · **Posted:** Wed Apr 06, 2016 9:34 am

Right, to say this coolant loss is doing my head in is an understatement! :banghead:

After finding traces around the heater hose I have lost more coolant but found NO MORE glow or wetness around these pipes!? (A red herring?) ( In fact i cannot see any more traces of uv dye anywhere. Yet i find it hard to believe I have such a coolant loss internally that gives me;
No contamination in oil
No white smoke
No smell of coolant in exhaust
No bubbles in expanaion tank
No pressure at cap when engine cold
Absolutely no issues driving including trailer towing 1600/1700 kg
No variations in temperature

After speaking with a VM specialist here in England he advises against a compression test - too many false passes/failures. So next step for me would be the HG test for exhaust gasses in the coolant, the one where the liquid will change colour etc.

So my first question if anyone can help;
If there is any leak between coolant and engine - is it possible that coolant could leak into combustion but no gasses into the coolant?
Surely if I hook up this tester and then start engine from cold all the way up to operating temp and then even 3000rpm+ and i get a pass - surely there is NO leak internally? (i'm happy there is no leak to the oil as the coolant is squeaky clean and the oil is perfectly black and steady level.

And my second question;
Does anyone know of any mythical fairy like creature with a fondness for squirreling away coolant while I sleep? :lol:

trying my best to avoid a £1500 bill for new HG and possible head when car is worth £2500

geordi · **Posted:** Wed Apr 06, 2016 10:53 am

I seriously doubt you are having the head issues as you describe if the cold engine test (release pressure on cold engine, start and run for 1 minute, shutdown and check pressure) shows no pressure in the water system.

If you aren't having bubbles into the water bottle and nothing in the overflow side of the bottle, then I would still look elsewhere. You found leaks at those hoses. I would start there, replace those hoses or at least bypass / loop them together for a test and try again. I don't prefer the compression fittings that your hoses show they have - those aren't 100% secure and can eventually leak - and just because you haven't seen the water, it is obviously still coming out as you are driving. Those hoses are the most likely source. Even if you have to buy them complete from your local auto parts shop, it will be one less leak point and then you can look elsewhere if the problem persists.

Mountainman · **Posted:** Wed Apr 06, 2016 11:21 am

I would remove the cap on cold engine and have someone slowly bring the idle up to 2k or so, and shine a bright light in the reservoir. I have found tiny bubbles this way, and I could see them without a light. Although at your rate, just a light at idle should show any, since you have a massive leak. Maybe you could have someone follow you on the road also, and maybe they would be able to see white smoke that may dissipate before you, the driver, can see it. Warm engine for that test.

Fern30 · **Posted:** Wed Apr 06, 2016 2:24 pm

Thanks for all the replies guys they're all much appreciated and will keep you posted. Gonna replace the heater pipes and fill tank again and eliminate that first and keep going! .

Fern30 · **Posted:** Thu Apr 07, 2016 3:27 pm

Found a glow further down the engine. Coincidentally right below where i found the first signs on the heater matrix pipes. Will get them replaced and see if we have any further leaks?

WWDiesel · **Posted:** Tue Jun 07, 2016 11:40 am

Anyone needing to test for HG leak, ToolTopia has a Combustion Leak Tester kit on sale right now for less than 50 bucks, not a bad deal if you are need of one... :wink:

http://www.tooltopia.com/uview-560000.aspx

Test for HG failure or EGR cooler? Coolant leak.

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