Coolant Leak...Somewhere

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profdlp

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Well, sort of done but not quite.

The coolant reservoir I bought is the wrong one. It is for a closed system and my Jeep has the open system they switched to late in the KJ run. I have run into this before, most notably with my KK PCV valve. I will return it and try again. I think I can replace that without having to drain the whole dratted mess again.

Speaking of draining, I got very little coolant out. The radiator petcock dribbled away for a good long time. (Several hours, while I was fiddling with all the other stuff.) I also replaced the hoses and thermostat, which one would think would allow everything to drain really well. Even so, I got only a gallon or so out. So, there is either roughly two gallons still in there or my coolant had been leaking far more than I thought. I first noticed the leak while it was parked in my garage and if I had to guess the amount that leaked there I would put that at about a quart. The little bit that missed the bucket while draining it today was on a concrete driveway and amounted to practically nothing. So, where is the rest? Dripped out all over town? Or still stuck in the system somehow? My driving these days is mostly three miles each way to the gym and four miles each way to church, barely enough time to get the thing up to normal operating temperature.

The last time I did this I recall having trouble getting the system filled. In fact, I remember coming here and one of the old-timers (I think it was TJKJ) suggested I pop one end of the lower hose and pour some coolant directly into that, which did the trick. The weird thing is that I could still see fluid when I looked in the radiator cap hole - it was like it never actually drained.

I did start the Jeep for about ten seconds and it fired right up. I did not want to let it run longer than that to find out if it was going to overheat. I have an add-on for my Garmin called the Garmin Mechanic which plugs directly into the ODBII and gives me my choice of a number of gauges, one of which is an actual temperature gauge. It has never exceeded 200F and normally stays at 196F once things are warmed up. Would you recommend my adding coolant and trying to let it run? I figure I could watch the temperature and if it went above 200F I could shut it down and then try real hard to have a brilliant idea. It may be that I had lost more coolant than I thought and maybe the leak was a blessing in disguise and alerted me to the problem before disaster struck.

What would you guys do next?
 
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profdlp

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Well, turns out the coolant was mostly gone. I am embarrassed to admit that when I saw coolant up to the radiator cap I assumed it was still full. I figured something was clogged somewhere and that was why it wasn't draining. I kind of forgot that there is a little shelf at the top inside the radiator cap area. I managed to get about two gallons of coolant into the Jeep.

My problem right now (assuming I actually even had one at this point) is that I am afraid to run the engine long enough to get the thermostat open. I get gobs of heat from the blower in the cabin so I know something must be moving through there. The top hose gets warm but the bottom hose not so much. I assume the thermostat has to open for that to happen and I am really leery of running the temp up too far. With an eye on my Garmin gauge I idled it until it got up to about 140F, at which point I chickened out. (Bwauk Bwauk Bwauk.)

Since nothing can ever be easy or straightforward, my current problem is that I can't get the lousy bleed setscrew to budge. I am dangerously close to stripping it out and it won't move even a little. I've got it soaking with WD40 and will try again soon.

The reservoir was filled to the "normal" mark and hasn't moved either way.

When I last had it in the shop the mechanic told me he thought there was an oil leak. This was not too long after I had to replace a leaky oil sensor. Oil levels have stayed normal ever since. In fact, until that happened I had never needed to add oil between changes. Knowing what I know now I think it was my coolant dripping down underneath. After wrestling with this the past few days I have been reminded just how greasy coolant can feel so I am pretty sure that is actually what the mechanic was seeing. The oil on the dipstick was still in the normal range when I checked it again today.

The good news is that thus far I do not see anything dripping so I am hopeful that the water pump was the issue all along. I remember having a good bit of trouble getting the system refilled when I changed the water pump previously.

At what temp does the thermostat open? Is it safe for me to idle the engine until it reaches that point? I will also need to drain this again as I was using some 50/50 I mixed up some time back and I want to ultimately get it filled with the fresh coolant I just bought. I wanted to get things circulating really good to help flush things out so I intentionally used the leftover stuff I had since that was going to be a temporary thing anyway.
 

lfhoward

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Hi Prof, my Jeep runs at 206° so I think you have plenty of leeway before the thermostat kicks in. I think most 3.7L thermostats are set for something around 195-200°.

The last time I changed my heater core was the last time I had to bleed air out of the system. The bleed screw was completely seized like yours. I was able to park the Jeep nose-up on a hill, take the radiator cap off, crank the heater, and start it up and run it for 20 minutes or so. All the trapped air seemed to come out of it. If there was any left, it must have worked its way out over the next several drives.

I have a laser thermometer so I was able to keep tabs on the engine and cooling system while everything was happening. My ScanGauge also reports the coolant temperature way more precisely than the temp gauge on the dash. If it was going to overheat I feel like I would have been able to shut it down in time.
 

profdlp

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I remember hearing of the ScanGauge when I got my Garmin add-on. I trust my Garmin Mechanic a lot. I always have the battery, coolant temp, and speedometer visible. They let you pick from around a dozen but you can only display five at a time. I know on a hot day in stop-and-go traffic the temp will run up to 207 or so, but only very briefly. As soon as you start moving it drops right back down again. So I think I will give idling it for a while a try. I do not have a fancy laser thermometer, though.

Do you think if I put the front end up on ramps that would help bleed the air? And to what temperature can I run the thing with the radiator cap off before something bad happens?
 

eric1514

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Don't worry about the bleed screw. The Factory Service Manual makes no mention of it in the cooling system filling procedure, anyway. It says to just fill the reservoir, run the engine a few minutes, and if the level goes down, let it cool a bit and add more coolant. Rinse and repeat. Keep the cap on at all times. The system will bleed itself but only if it can create pressure and vacuum and it can only do that with a closed system.

Also, the lower hose should be cooler than the top. Hot water enters the top of the radiator, cools on its way to the bottom and exits back into the engine hopefully cooler than it went in. That flow through the radiator only happens when the thermostat is open.
 
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lfhoward

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The KK has an open system and Prof’s 07 is a transitional year with an open system too, I think. By open system I mean the overflow bottle is not under pressure.
 

profdlp

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Yeah, that's how I ended up with the wrong reservoir. (Now back in the box waiting to be sent back. Fifty bucks for a plastic jug!) I've had a couple other little things over the years which, when I finally figured out what I actually needed, the site didn't want to sell them to me because they were sure it wouldn't fit my '07. :rolleyes:
 

profdlp

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I don't remember exactly which site. I think it was when I replaced the PCV valve and found out that my '07 uses the one for the '08 - '12 KKs.

So, got some coolant in but seemed to have trouble getting it all the way to the lower hose. I looked this morning and the level in the reservoir had dropped a fair amount. I was busy today so might get to work on it tomorrow.

And...just like 12 years ago, the o-ring on the @#$%^&*! petcock decided now was a good time to give up. Drip...drip...drip. I am being philosophical about it since I planned to drain it all again after letting the temporary coolant circulate for a day or two to give it an extra flushing out. :)
 

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Went to the gym yesterday and got home with no problems. Came out this morning and saw fluid seeping across the garage floor. Checked the coolant and the reservoir is empty and the radiator level is down about an inch from where I usually see it.

Crawled around underneath and saw a good bit of coolant coating things underneath but no obvious spots where it could be coming from. The upper and lower hoses look good to me, but who knows...

Any suggestions on where I should be checking and how to test it?
I had a similar experience, it turned out to be the tank on the driver's sider of the radiator. The coolant used in the mid 2000s Jeeps seems to dry quickly when on a hot surface which made finding the leak difficult. I ultimately had to run the engine and warm it up and inspect everything as it warmed up. It took a few tries before I finally spotted coolant coming through a hairline crack in the radiator tank.
 

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My '02 had the small crack near the top left tank of the radiator. At first it looked like the hose was leaking, but watching it run when hot and under pressure could see the hairline crack. I believe that is a common problem on the factory radiators and no JB Weld plastic repair would not stop it for more than a couple of days to a week. Finally replaced it with a new Murray from O'Reilys, which was a chore with the heavy duty cooling/ mechanical fan and very little room. Been good for about 10 years and 40,000 miles. Just refilled with new coolant and let it bleed the air over a couple of cycles.
 

profdlp

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Well, so far, so good. I wasn't going to work on the Jeep yesterday but came home from church and decided to at least try and fix the petcock leak. (This is a new one, the o-ring apparently was on its last legs and didn't have one more "close" cycle in it.)

Filled the radiator, etc., and ran it until the temp hit 200F (briefly). Heater was blowing the hottest it's felt in years, though on a 65F day that doesn't mean as much as it would if it were single-digit temps out. The coolant temp behaved normally. Idling in the driveway I would expect it to get to about 196F, then rise and fall very slightly as the fan kicks on and off. And that is just what it did. I could see lots of bubbles at the top of the radiator.

And no leaks anywhere! It was still dry as a bone this morning and just a few minutes ago when I checked it again. I am hoping to drain it again tomorrow and get the right mix of fresh coolant in there. If I manage that with no leaks popping up I think I will be done.

A funny thing that I thought of for the first time yesterday: When I had all the trouble refilling it the last time I did the water pump I was parked on the street with the Jeep nose down on a slightly steep hill. I bet if I parked with the nose uphill things would have been easier. Yesterday I was slightly nose up and it went very smoothly.

And since there always has to be "something", is it normal for the A/C clutch to keep kicking on and off? It was clacking fairly steadily.
 

profdlp

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Rats.

Got it drained and refilled with new coolant. Everything went just fine. Finally got to the point where it seemed to have all the air out of the system and took a short test drive. No problems.

Got home and saw a pinhole leak at the top of the radiator right where the top hose is connected. There is a flat shoulder and the hole was right in the middle of it. It is very tiny and the leak is not really a spurt but just a really small spray. I do not know if this was there before since it has only now appeared, but that is certainly possible. I do think the water pump was the main issue as there is no way the coolant I got on the garage floor a week ago came out of the little pinhole. If it was there before I suspect I am only seeing it just now because I never had the system completely burped before.

Is there anything I can do?

The pinhole is directly under where the red arrow is pointing on top of the shoulder of the radiator.

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eric1514

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Rats.

Got it drained and refilled with new coolant. Everything went just fine. Finally got to the point where it seemed to have all the air out of the system and took a short test drive. No problems.

Got home and saw a pinhole leak at the top of the radiator right where the top hose is connected. There is a flat shoulder and the hole was right in the middle of it. It is very tiny and the leak is not really a spurt but just a really small spray. I do not know if this was there before since it has only now appeared, but that is certainly possible. I do think the water pump was the main issue as there is no way the coolant I got on the garage floor a week ago came out of the little pinhole. If it was there before I suspect I am only seeing it just now because I never had the system completely burped before.

Is there anything I can do?

The pinhole is directly under where the red arrow is pointing on top of the shoulder of the radiator.

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I once repaired the radiator on a motorcycle with this stuff.

J-B Weld Radiator Repair

It lasted the for the 5-6 years I owned the bike and was still sealing when I sold it.
 
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profdlp

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I ordered the J-B Weld and it is supposed to be here tomorrow. I see where a lot of people do not think it works but I know when it comes to things like this proper preparation and application make a huge difference. Plus, this thing is truly just a pinhole. I would imagine a lot of people would try fixing the gash on the Titanic with sealant, then be disappointed when it still sank.

I have been looking at a few videos on radiator replacement and it does not look as awful as it first seems. Of course, any type of work looks easy when someone else is doing it. :D I'd rather not be trying to do it if it was freezing cold out,but if the patch can get me to next spring it would be very much worth it. I think I'm going to need to have a look at brakes pretty soon, too.
 

lfhoward

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The JB weld option is what I would try first too. I think with such a small pinhole, and doing careful mixing of the epoxy and surface prep, it should hold. Hopefully it will hold for a good long time, way longer than next spring. ;)

For the brakes, are you looking at all four corners, both rotors and pads? I'd be interested to know what brand you go with when the time comes. My shop recommended brakes soon when I got my yearly PA inspection. They are getting there, just not low enough yet to fail inspection! Does Ohio have state inspections? I know Michigan doesn't.
 

profdlp

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It would be wonderful if it were a long-term repair. I would welcome the advice of anyone who has tips on how to do it right.

I won't know about the brakes until I look, but I think it will be rotors and pads for the front at the least. I did all the brake pads front and rear about a year and a half ago. The rotors were all done about 30,000 miles ago. I'll include a barely legible screenshot of that order. It was all NAPA premium stuff.

We do not have a scheduled inspection here in Ohio. In some counties the State Troopers will set up a roadblock and do random checks, but I have never encountered one here in Cuyahoga Co. When I was still a Virginia resident I was visiting relatives in southeastern Ohio and went through one. They waved me right on by when they saw my VA tags. Virginia has an annual inspection. (When I was young it was semi-annual, which really stunk. Every six months...) You had it done at the mechanic of your choice and lots of shops viewed it as a nice revenue stream. You can always find something wrong if you look hard enough.

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eric1514

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I think when doing the epoxy repair the most important thing is to make sure the surface is clean and not oily. Use a lot of brake cleaner. My repair was more in the fin area so I couldn't scuff the surface up, but if you have the room, I would rub the area with a scotchbrite pad and then clean it again with brake cleaner. Many good lucks.
 

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