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Test for HG failure or EGR cooler? Coolant leak.
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Author:  Fern30 [ Sat Mar 26, 2016 3:54 pm ]
Post subject:  Test for HG failure or EGR cooler? Coolant leak.
Hi all,
After years of Volvo, and even a SSangyong (Don't ask!)! I'm back with a Cherokee CRD. 2.5 CRD manual.(Liberty) I have a coolant leak and for the life of me I cannot find the flamin thing! :banghead:
New thermostat and gasket.
New expansion tank cap.
NO VISIBLE signs of a leak anywhere! On any pipe or floor after engine hot or cold.
Re HeadGasket failure - a little white smoke within first 2 mins of cold driving. Completely gone after that - no smoke.
Oil level static - not increasing and no contamination?
No bubbles in the expansion tank, all hoses just firm when up to temp and not solid and after a min of engine running cold, no pressure in expansion tank.
No codes/misfires or rough running at all?
After all of that, going to buy a pressure test kit. Hoping that will show up a pressure drop BUT if it doesnt highlight a pinprick leak somewhere onto the engine thats drying straight away I'm going to presume its leaking internally somewhere.
How do I tell HG failure over EGR cooler leak? And if either were true woudn't I get white smoke all the time?
Does the EGR cooler have an internal gasket that leaks coolant into the exhaust or will it be split inside like a rad?

Completely lost!!
Author:  papaindigo [ Sat Mar 26, 2016 4:19 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Buy some UV coolant dye; put in coolant tank; drive for a few days; park the vehicle in a shady or dark area; look for dye marks with UV light (be sure to check ALL potential leak points including drip tube from cabin AC/heater core. I once chased a totally invisible leak the UV dye showed was due to a weak OEM spring clamp on the lower radiator hose; slow drip that immediately evaporated.

Little white smoke at first crank up doesn't tell you much; some do it (my son's 06) some don't (my 05).
Author:  Fern30 [ Sat Mar 26, 2016 4:29 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
I suppose cheaper than the pressure kit. Worth a fiver to check for external leaks first - will post results!

Edit - Ordered-heres hoping! :wink:
Author:  buddy357 [ Sat Mar 26, 2016 4:37 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
I remember one of the suggestions for checking a potential head gasket leak. It was to let the engine sit long enough to be ambient temp and there should be no pressure in the overflow tank. Crank the jeep, let it run about 30 seconds to a minute and see if the bottle is now pressurized. If it is, you have a head gasket leak.
Author:  flman [ Sat Mar 26, 2016 5:15 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Why not try something like this?

http://www.amazon.com/UVIEW-560000-Comb ... B000NPDL76

Any pressure under the cap 1st thing in the AM, before you start it? Should be no pressure, or maybe slight vacuum.
Author:  Fern30 [ Sat Mar 26, 2016 5:28 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Done that, doesn't explain it well in my original post but when the engine is cold. No pressure. Turn on and run cold for a few mins then release cap - still no pressure. Which i suppose is it least good? Worried its a HG leak but I've got nothing that tells me it's that - except the mysterious leak? Lets hope the UV dye shows something.
Thanks for the pointers.

Not tried the exhaust gas detector though..................
may be next if Uv doesnt work?
Author:  geordi [ Sat Mar 26, 2016 7:00 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
How often are you having to add coolant (getting the alarm) and how much are you adding each time? What is the top level you are aiming for - the seam in the middle of the bottle or higher?

Is there anything in the overflow side of the tank? You probably have a RHD model, and I don't know if the coolant tank is mirrored or if it is located in the same place as on the USA versions... But on the USA versions, the overflow is the section of the bottle closest to the centerline of the engine. That section should be dry normally.
Author:  flman [ Sat Mar 26, 2016 7:01 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Fern30 wrote:
Done that, doesn't explain it well in my original post but when the engine is cold. No pressure. Turn on and run cold for a few mins then release cap - still no pressure. Which i suppose is it least good? Worried its a HG leak but I've got nothing that tells me it's that - except the mysterious leak? Lets hope the UV dye shows something.
Thanks for the pointers.

Not tried the exhaust gas detector though..................
may be next if Uv doesnt work?


A few people had their block crack at the top in the water jacket, and I am pretty sure the fluid evaporates or spreads enough back there making it un detectable.
Author:  flash7210 [ Sat Mar 26, 2016 8:18 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Pressure test the cooling system.
Then pull out the glow plugs and unplug all four injectors.
Then crank the engine.
If water comes out the glow plug holes either your head gasket is blown or your head is cracked.
Author:  Fern30 [ Sun Mar 27, 2016 7:00 am ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Get the alarm every 200-250 miles. Top it up to the seam in the middle of the tank. No water in the expansion side. I'm hoping that at that rate if it was leaking into engine I would see some kinda white smoke pretty much constantly? Just worries me the other way as well though - it's leaking that much out over that mileage and i don't see ANY on the floor or underneath/in engine bay etc.
Swear the fairies are nicking it nightly !!

If the UV dye shows up nothing will have to start looking at pressure test then pulling the plugs......
Author:  Billwill [ Sun Mar 27, 2016 11:00 am ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Fern30 wrote:
Get the alarm every 200-250 miles. Top it up to the seam in the middle of the tank. No water in the expansion side. I'm hoping that at that rate if it was leaking into engine I would see some kinda white smoke pretty much constantly? Just worries me the other way as well though - it's leaking that much out over that mileage and i don't see ANY on the floor or underneath/in engine bay etc.
Swear the fairies are nicking it nightly !!

If the UV dye shows up nothing will have to start looking at pressure test then pulling the plugs......


The early Export 2.5 CRd did not have coolant pipes for the EGR...don't know about yours!

The radiator cap not showing a creamy goo on the underside? :?
Author:  geordi [ Sun Mar 27, 2016 6:00 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Ok, that sounds like a massive leak. Definitely get the UV dye, and then fill it up right to the tippy-top so it won't take another drop. You won't bother anything with that, and hopefully it should make the results more impressive. Getting a coolant alarm that often is startling to me, that would be just about every day that I'd be adding water at that rate! You should be able to see SOMETHING with it draining that fast.

The inside of the water bottle isn't black, is it?
Author:  Fern30 [ Sun Mar 27, 2016 6:46 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Bottle is as clean as a whistle! Like i said at that rate i would expect clouds of white if it was the HG? But likewise pools everywhere for an external leak?

Anyway, UV dye on the way, should be here next week - keep you posted !
Author:  Lancer [ Sun Mar 27, 2016 6:56 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Check the hoses at the thermostat. Mine suddenly started losing coolant at about 500 ml per 5-600 miles. No white smoke, oil seemed fine. Took it to my local dealer - I've been going to this mechanic since I bought the Jeep 10 years ago. Pressure test was fine. Turned out the clamps on the hoses at the thermostat had somehow loosened and coolant leaked out as I was driving and evaporated off - hence no puddles either.

Might not be your problem, but checking won't hurt!
Author:  Fern30 [ Sun Apr 03, 2016 11:00 am ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Got the dye today, Ring RLD2 Uv dye for coolant. Put it straight in and went for a half hour drive. Got back and just been under the car and I'm none the wiser!!?? Couldn't find any traces of anything so to test, dipped my finger in the coolant tank and smudged it onto the air filter box. Shone my blacklight over it and it DOESN'T 'flouresce' or glow or light up or even look any different than the rest of the filter box. Even waited for it to dry - still nothing? Covered it up to darken the area - still nothing.

So for all I know my engine bay could look like the sky at night but seems the dye doesn't work? :furious:
Author:  lars0247 [ Sun Apr 03, 2016 4:36 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
There was a crack in the head on mine. It was in the intake pocket, so there was never bubbles in the coolant since the crack was never exposed to the high pressure of the cylinder. Found that I had a leak by pressurizing my cooling system to about 12 psig, and leaving it overnight cold. When it would not crank over the next morning, I knew it was hydrolocked, which I confirmed was the case on teardown.

Got a low-mileage test head from the VM Specialist in the UK with ARP studs. Works great now.
Author:  geordi [ Sun Apr 03, 2016 4:54 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
How dark is the environment around the car? I don't know how bright the dye will glow, but I know it won't look like on TV. Especially during the day. You might need to have a look after dark, or in a parking garage or someplace as dark as you can get it.


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Author:  Fern30 [ Sun Apr 03, 2016 5:32 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
You could be bang on there Geordi!
Just nipped out (pitch black now), and the expansion tank glows like an alien! Took it for another run, only 10 mins and had a good look again. No great splashes anywhere BUT spotted some coolant with the uv light :D

There are 2 heater matrix pipes going across the top of the engine. Where they go back to rubber just before going through the bulkhead they are covered in a protective mesh. The tape that was wrapped around the pipe to hold the edge of this mesh was glowing green and slightly wet?
I swear there was an ever so slightly green haze over the top of the engine here although that could be me just "hoping"! I think there may be a pinhole somewhere here thats almost atomising straight away?
Anyway this will be where i'll keep looking and if it is the culprit over a few days it should light up in the dark?
Does coolant flow continuous through the heater matrix or is there anything i can do to help/ensure it leaks as much as possible?
Author:  flman [ Sun Apr 03, 2016 6:50 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Fern30 wrote:
You could be bang on there Geordi!
Just nipped out (pitch black now), and the expansion tank glows like an alien! Took it for another run, only 10 mins and had a good look again. No great splashes anywhere BUT spotted some coolant with the uv light :D

There are 2 heater matrix pipes going across the top of the engine. Where they go back to rubber just before going through the bulkhead they are covered in a protective mesh. The tape that was wrapped around the pipe to hold the edge of this mesh was glowing green and slightly wet?
I swear there was an ever so slightly green haze over the top of the engine here although that could be me just "hoping"! I think there may be a pinhole somewhere here thats almost atomising straight away?
Anyway this will be where i'll keep looking and if it is the culprit over a few days it should light up in the dark?
Does coolant flow continuous through the heater matrix or is there anything i can do to help/ensure it leaks as much as possible?


The coolant goes through the heater core continuously, it has baffles to divert heat or cooling.
Author:  geordi [ Sun Apr 03, 2016 7:13 pm ]
Post subject:  Re: Test for HG failure or EGR cooler? Coolant leak.
Yep, the heater core is fed continuously with coolant. A pinhole sounds about right, although I'd like to see this "wrap" you are talking about, can you get a picture? It sounds like someone might have had a leak previously and tried to fix it with some self-sealing repair tape, and that is what you are experiencing. I know from experience that the rescue tapes are great, but they aren't 100% pressure-tight. There is always the chance for some leakage.


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