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Discussion Starter · #1 ·
One of my '03 AWD with 173K miles is testing me. I'm always looking for drips and noticed several weeks ago that my front cross member where idlers attached was wet, mostly on DS, and the moisture appeared to be coolant. I hadn't check the system lately and the reservoir was low. Topped it off and began to monitor as well as look at common coolant leak areas. Occasionally, the cross member would be wet and then I noticed by the upper rad hose it appeared to wet and running down DS of radiator. Forum search revealed that this was common failure point. I squeezed the clamp and slid the hose farther up on the mount. Reservoir had gone down slightly, maybe less than 1". The van mostly gets just driven around town right now, and after one 30-minute trip while checking upper rad area I heard gurgling after the engine was shut off. There were bubbles in the reservoir. Pull the oil dipstick and it's beautiful clear like amber maple syrup. Still can't see any drips anywhere else in the engine bay or underneath. Occasionally, the upper rad area was damp but seems less now. There is a hint of white smoke a few seconds after startup that literally disappears after one minute of running. I do live in a high desert area and it's been unseasonably cool so far this spring. Yesterday, after another short trip, once home I left the van running and checked the reservoir only since the rad was hot and it was bubbling away. URG.

The LIM was done about 20 months and a few thousand miles ago. The van has been running perfect, holding temp a bar and half left of center, idles perfect, oil level perfect....basically, if I hadn't seen the moisture and found the reservoir low and now the gurgling I wouldn't have thought anything was amiss. I did search and read I think all of the coolant, LIM, head gasket threads last night and admittedly, mainly since the weather has been crap here in OR, I haven't done a pressure test, exhaust gas test in the reservoir, borescope cylinders to see if a piston head is shiny or pulled the doghouse to check on the rear of the engine but nothing is making it to the ground that far back nor can I see anything up higher. Head gaskets seem rare according to everyone so has the LIM failed again? Can a failed LIM mimic a head failure with bubbles in coolant? (I couldn't find that in anyone's posts last night but could have missed it) I do plan to start the engine cold with the cap off and see if there's bubbles once the engine warms up, which I suspect will be the case. Thoughts?

P.S. I know I've broken the pics/video rule but if it isn't raining, sunny, snowing, and blowing it's sunny, then snowing, blowing and raining so my apologies.
 

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It sounds like a radiator tank leak, or possibly leaking from the core it’s self…. Or at least I would absolutely rule it out….
The pressure test should tell all.

If you can reach in behind the fan with a clean paper towel and blot the core the coolant should show up if it’s the core.
Good opportunity to upgrade to one of the all aluminum radiators from eBay. 👍🏼
 

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I went through this couple months back. Couldn’t find the leak. So I took it to my mechanic and wouldn’t you know it the leak was very small. Ended up with a new radiator and new transmission cooling lines. Can’t afford an overheated 4.3
 

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Bubbles in radiator is one of the signs of a blown head-gasket. So is white smoke when first started, or moisture out exhaust pipe. These could also be signs of LIM gasket too.. but since you just changed it I would be more inclined toward head gasket.

Another sign of head-gasket issue is using coolant without finding a leak.
As far as head-gasket, hey make combustion testers for the radiator.

Compression tester will not reveal blown head-gasket. Leak-down testers are supposed to, but in my case it didn't either, bad cylinder also showed fine... however pressurizing the bad cylinder pushed air bubbles into radiator. My leak must have been tiny.

Not saying this is your issue, but it was mine. Another sign is misfire codes for the leaking cylinder, which mine developed after some time.

Keep an eye on coolant level. Also be aware that sometimes when issues like this develop, the reservoir doesn't always function correctly.. meaning the radiator could be low even though reservoir appears full. Pull cap once in a while to be sure it's actually full and reservoir system is functioning correctly.

If you simply have a coolant leak somewhere.. then consider yourself lucky with an easy fix. Pressure test the radiator and look for the leak. Thankfully it's not going into the oil

But actual bubbles in radiator (especially when you rev engine) is not good. Gurgling is not the same thing.
And you are correct, you want to avoid overheating the 4.3.

Good luck
 

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Discussion Starter · #5 ·
Thanks everyone for their replies. I'm praying it's the radiator so I could upgrade as well as avoid a head gasket issue. If for some reason it's the LIM again, oh well but still better than the head. One thing I wonder during the pressure test is should I put it on the reservoir so the cap can test too or straight on the radiator? Looks like I've seen both ways. If the upper rad hose connection or core is cracked/compromised or the cap is bad, can that lead to the same bubbles in the coolant like a head gasket issue? I've cautioned my daughter, it's really her van but dad drives it a fair bit, to keep an eye on the temp gauge to avoid an overheat and fortunately, so far, it's been rock solid. I'll wipe down the core and see if I can detect anything as well as run it with the cap off. I've read that if it's a head gasket and it's leaking into a cylinder that the piston head off the compromised cylinder should be clean and I should be able to see this through the spark plug socket, correct? This would seem to be more foolproof than what Mmusicman experienced. I changed the fuel filter about a month ago, and while on the scanner all diagnostics were good, with no misfires being recorded. Again, the level drop in the reservoir has been small and the white smoke is literally a whisp but maybe that's just hinting at that it's tiny leak at this point.
 

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Discussion Starter · #6 ·
I should add that when I checked after the engine had cooled and the reservoir had lowered but still with plenty of coolant remaining that the radiator was full, implying that reservoir system is functioning correctly.
 

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One thing I wonder during the pressure test is should I put it on the reservoir so the cap can test too or straight on the radiator?
No, the reservoir is not part of the pressurized system.
Also, you're not testing the cap.. just the coolant system.
Caps are cheap.. just replace it if you are uncertain.
 

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I'm not usually a fan of "mechanic in a bottle" but if it's a minor leak this stuff actually works without any side effects. My Dad swore by it and I've used it since I started playing with my own cars in the 70's.

It's aluminium powder and it floats freely in the coolant until coolant gets pulled through a leak. After a bit of time it builds up a layer of particles until the leak is sealed. It also helps to lubricate the water pump.
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Obviously it's not going to fix a head gasket but if its a small leak where a gasket may be deformed or a pinhole in the radiator, it has been known to work.
 

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Discussion Starter · #10 ·
Just an update...when my daughter got back today I checked things after the van had cooled down. Reservoir level was the same and the only moisture I could find was on the DS radiator mount and there appeared to be some weeping around the upper rad hose connection but nothing on the radiator in between the two locations. I think it's possible that engine bay heat, the wind today, and low humidity (I live in the desert) may have evaporated any along the DS of the radiator. Since the cap was cool I did loosen it to the first turn and I could hear pressure being released and then when I started to turn it farther coolant came gushing out so I quickly closed it. I'm going to try to pressure test it tomorrow but it would seem that the system was holding pressure given what happened when I loosened the cap.
 

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Also check around the water pump, I once had a car that leaked on one tiny spot on the water pump to block mating surface. Took forever to locate it. I simply took the water pump off and put new gaskets and it was fixed.
 

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A very common place for leaks is the heater valve. They crack.
Tricks you because it mixes with A/C condensation which exists on same side.

I live in South Florida.. neither of my vans have heaters hooked up anymore. No hoses, no valves, no coils to fail.
 

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Discussion Starter · #13 ·
I haven't seen anything around the water pump or the heater valve.

The van hasn't been driven since Saturday afternoon. Not the best pictures but I did notice this today in between snow thunder cells. I wonder if this could be the problem. I hope to do a pressure test today but I'm not sure if the weather is going to cooperate. And despite the weather this is not moisture from outside as the van hasn't moved and nothing else is damp in the engine bay. Looks to be maybe some weeping around the cap, which is the non-OEM 16 psi one.

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Actually, it's quite common for those plastic tanks to leak.
Not likely the cap as overflow should go to the reservoir.
(I run the same cap)

I see it's under the hose.. which could also be leaking

You said you opened it the other day and fluid came gushing out.
Could still be just remnants of that too.

Once you do the pressure test.. you can stop guessing.
 

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Discussion Starter · #15 ·
Update...weather allowed me to do the pressure test on cold system. Cap tested fine at 15-16 psi. I wiped everything dry, mainly near the upper rad hose connection. Charged the system to 15 psi and it held for 30 minutes with no leak down and no leaks detected anywhere. Removed the pressure tester and started the van with the cap off to see if it would gurgle while running but the coolant dropped and then began to rise to overflowing. I put the cap back on and ran it until the thermostat opened and then for 20 minutes longer with both front and rear heat on nearly full blast, increasing the RPMs several times too. The upper rad hose did weep for a moment but then nothing more and there was no gurgling ever in the reservoir while it ran. I would have to assume that if the head was bad I should have seen bubbles while running. Further, it was about 40 degrees today and I did have some light white smoke while idling and I held my hand under the tailpipe and it was pure water. Not only did I smell it but I tasted it too - crystal clear. While looking around I did notice a drip of coolant too through the DS wheel well on the bottom corner of the radiator, which I'm guessing came from above.

I ran the pressure tester back to the LAPS in the van, about 20 minutes roundtrip and no changes at upper rad hose but reservoir was gurgling once back and engine shut off. I let everything cool during supper and went out to look again. Upper rad hose more weeping and slight drip forming at DS bottom corner of radiator (see pics). I'm guessing that this is my issue and it's a tiny leak (for now). Suggestions for simplest aluminum radiator, direct-fit with mounting tabs are welcomed since looks like I'll be changing a radiator at some point unless someone suspects something different.

Thanks for everyone's help.
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Discussion Starter · #17 ·

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Discussion Starter · #18 ·
We took a drive Wednesday night in the van, and Thursday morning the there was a good bit of coolant on the ground and the radiator was low but not the reservoir. I was in a predicament because I'm headed out of the country for work for a few weeks and our daughter wants to drive. In a time crunch, I got a quote of nearly $1,000 to replace the radiator as well as hoses and t-stat if needed. Strategized Thursday night and determined I could get an OEM radiator at the LPS, which I did and installed it this afternoon so the van could be back on the road while I was gone. Yes, I wanted to do an aluminum radiator, and thanks again Sailing_Faith for the link, but maybe I'll do it on the other '03 or '02 or both. After pulling the radiator I was VERY pleased to find the problem (see below). It was weeping from near the upper rad hose. When you flexed the connection it really opened. I like it when the story has a good ending. Thanks again everyone.

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Actually, it's quite common for those plastic tanks to leak.
Glad to see it was something simple... BUT even more happy to see you fixed it YOURSELF! They are not difficult to change and look how much money you SAVED! Nice sense of accomplishment too.

PS: The stock replacement will be just fine for regular use.
You got it done!

Enjoy
 
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