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Post Number:#1  PostPosted: Sun Apr 01, 2007 9:51 pm 
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I have have had an unusual radiator problem for the last four years.

I had the radiator cleaned, rodded out, and repaired recently, 3 weeks ago and the unusual problem did not go away.

The system works normally and runs fairly cool while the engine is running (170 winter, 215 summer with A/C on at 100 F ambient). It is an open system with an overflow bottle. The problem I have is that the coolant in the overflow bottle, about 80% of the time, refuses to return the radiator when the radiator cools down overnight. Sometimes it has returned to the radiator in the past, like 20% of the time, but since I got the radiator rebuilt it has not returned on its own, yet.

There are no external leaks anywhere and have not been any for 3 years ( I would have noticed). The radiator had a small leak at the top of the radiator tank that sealed itself (good use of radiator sealant) but that got properly soldered at the radiator shop a few weeks ago, so it is no longer a possible source of air getting into the radiator during cooldown.

The overflow bottle and return hose is air tight, no fluid or air leaks, the radiator cap has been replaced and tested with several brands and cap pressures over the last three years (tried 5 new caps). The overflow nipple on the radiator cap throat is OK. I have put 20,000 miles on this beast while I had this problem. I just manually poured the coolant back into the radiator each morning if the coolant bottle was full. The engine/radiator system runs cool. The overflow quantity is normal.

I have run out of ideas. Any one else ever had this sort of problem and found a solution, or figured out what was causing it.

I thought it might be something like a water pump seal going out, but its been doing this for 20,000 miles since 2003!

Its a 1985 jeep radiator (was 2.5 Liter gaser) in a jeep Cherooke Pioneer , with a Nissan SD22 diesel transplanted engine with a manual tranny so no tranny fluid in the radiator. Absolutely no engine problems and no coolant/oil mixing, etc. Everthing is normal except this da#n coolant return problem. Oh, and all the coolant hoses are only 12 to 18 months old. I am currently running a 13 Lb. pressure cap and the overflow that does not return to the radiator is about 1 quart.

So what's my problem???? Help, need ideas, Johnny-five needs input please!

Thanks!

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Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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Post Number:#2  PostPosted: Sun Apr 01, 2007 10:31 pm 
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This post has good info for your problem, specifically:
asavage wrote:
The reservoir will only replenish the radiator if the cooling system has integrity. If there's a leak, a vacuum won't form when the engine cools down, and the 2 PSI valve in the radiator cap won't open and allow coolant to be drawn into the radiator.

Also, if there is even a pinhole leak on the hose from the radiator to the coolant reservoir, it'll draw air in on cooldown.

And, of course, if the radiator neck is deformed, the outer gasket on the radiator cap won't seal, and again coolant won't be drawn from the reservoir. I've seen a couple of damaged seal surfaces on radiator necks in the past.

I will add my own experience here-- the overflow hose nipple on my rad fill neck had a small crack low near the inside bend; impossible to see but leaked air (vacuum) easily and coolant only slightly which evaporated quickly enough to be missed by visual inspection. Temp. solution was to clamp the hose further up on the nipple and use a worm clamp as the stock spring clamp did not clamp tight enough.


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Post Number:#3  PostPosted: Sun Apr 01, 2007 11:35 pm 
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If it's not a leaking overflow hose, I'll put money on the water pump. I've seen it before: no leakage, but also no vacuum.

You've covered everything else I would have recommended.

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Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.


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Post Number:#4  PostPosted: Mon Apr 02, 2007 12:11 pm 
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I would reccomend replacing the WP, the seals on the wp can hold tighter under pressure and release itself without pressure. Or try doing a overnight pressure test of the cooling system, even tho it dosent sound like a bad head gasket- it would of gotten worse over the 20k miles.

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Post Number:#5  PostPosted: Mon Apr 02, 2007 12:28 pm 
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You have a tiny air leak in your system somewhere, which as already posted can be at the water pump shaft seal. BTDT and this can be a real bear to find. The problem is you can have a leak path small enough that air will leak through it but liquid will not. This tiny leak path allows air to be drawn back into the system instead of the coolant from the overflow bottle.

So while performing a liquid pressure test which is standard, you won't find the leak as it may be too small for any liquid to leak out of. If you were to completely empty the cooling system of liquid, and then pressurize the cooling system with air, and then do a soapy water check of all external parts of the system, you may be able to find the leak this way. If the leak is internal to the engine (crack or at head gasket), you still won't find it very easily.

I didn't used to think that you could have a leak small enough for air but not liquid. But I noticed when working on water systems in my dad's rental units while growing up that after I had shut off the water and drained the pipes in order to fix something, I would repressurize the system and hear air hissing out of the closed faucets. Once the water reached the faucet, hissing stopped, and no water would leak. Seems simple in retrospect but this was a real eye-opener for me.

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1982 Datsun 720 King Cab, SD22, 86K miles (sold)
1981 Rabbit LS 4-door, 1.6D, 130K miles (sold)
1996 Passat TDI 4-door sedan, 197K miles


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Post Number:#6  PostPosted: Mon Apr 02, 2007 2:16 pm 
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I just don't buy it beng the water pump. If had been the water pump all this time, it would have gotten worse over the last 4 years, 20,000 miles and begun to actually leak (IMHO). It does not loose any coolant at all and does not over heat at all, so I have ruled out head gasket leaks for now.

I just pulled the overflow hose and cut the badly strecthed (loose) ends off and reinstalled it, until I get to the parts store and buy some good vacuum rubber tubing. I think my problem has been this rinky-dink clear plastic tubing that came with the aftermarket overflow bottle. Also it must be over 3 years old.

The wierd part is it would on occasion refill itself. The only time the overflow bottle is needed (fills up) is on long highway trips and with the A/C running for about 20 minutes or more in 90 F plus heat. With out the A/C at 90 F and idling in the driveway it hits 165 F, thermostat opens and it can sit there running for hours and hold presure with out overflowing to the overflow bottle.

But as I said, I have seen the overflow bottle fill, and then over night refill the radiator on several occasions, but intermittently. I expect it be the hose now that I have pulled it off and seen how loose/stretched it had gotten at the filler neck.

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Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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Post Number:#7  PostPosted: Mon Apr 02, 2007 3:05 pm 
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Yes, im a bit skeptical of the wp shaft seal, because 20k miles is a long time. If the expansion tank hose wasnt the problem, I would try a overnight pressure test on the engine and see if any coolant comes out of the pistons after cranking it, or just see if it hydrolocks, unless there is some kind of compression service port that you can open up easy.

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Post Number:#8  PostPosted: Mon Apr 02, 2007 6:47 pm 
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ecomike wrote:
I have have had an unusual radiator problem for the last four years.

I had the radiator cleaned, rodded out, and repaired recently, 3 weeks ago and the unusual problem did not go away.

The system works normally and runs fairly cool while the engine is running (170 winter, 215 summer with A/C on at 100 F ambient). It is an open system with an overflow bottle. The problem I have is that the coolant in the overflow bottle, about 80% of the time, refuses to return the radiator when the radiator cools down overnight.


I showed my 100* outheat at 65 mph with 40* A/C. The temp showed mid 200 eng.

You need to confirm the right thermostat (has disc)
Right Thermostat

Another idea ... vacuum occurs while radiator coolant cools off. It would suck air any other than having coolant tank coolant.

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Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"


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Post Number:#9  PostPosted: Mon Apr 02, 2007 10:24 pm 
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ecomike wrote:
I just don't buy it beng the water pump.

Have you seen a water pump's seal? It's a rotating ceramic seal with a spring providing the face pressure -- in the "pressurized" direction. IOW, the seal's spring, that maintains the seal face's contact pressure, works better in the "pressurized" direction than the "unpressurized" direction.

Some WP leaks are the seal's face, others the spring cartridge's rubber bellows.

In the absence of other evidence, I'll put my money on the WP. But I'd change the overflow hose first, sure.

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Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.


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Post Number:#10  PostPosted: Wed Apr 04, 2007 10:42 pm 
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asavage wrote:
ecomike wrote:
I just don't buy it beng the water pump.

Have you seen a water pump's seal? It's a rotating ceramic seal with a spring providing the face pressure -- in the "pressurized" direction. IOW, the seal's spring, that maintains the seal face's contact pressure, works better in the "pressurized" direction than the "unpressurized" direction.

Some WP leaks are the seal's face, others the spring cartridge's rubber bellows.

In the absence of other evidence, I'll put my money on the WP. But I'd change the overflow hose first, sure.


Yap, seen em, done em, designed and serviced cleaned systems for em, including ultrasonic immersion units and glass bead blasters for cleaning and rebuilding their big brothers, mechanical seals especially them fancy expensive ones used in the chemical plants (Exotic alloys, bellows, even the everyday pump seals, type 40s). Had a buddy here who ran the John Crane MS repair center back in the late 70's and early 80's. Use to work with the Borg Warner seal guys nation wide too.

Not saying the seal can't leak like that, just having a hard time believing the leak would not grow into an external leak after 20,000 miles.

Also I just don't want to change the water pump!!! So I am practicing wishful thinking, you know, I'm like, using the Force! Where is Luke when I need him anyway.

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Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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Post Number:#11  PostPosted: Wed Apr 04, 2007 11:15 pm 
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Have you seen Luke lately? He's gotten old and fat like the rest of us.

OK, so you know rotating mechanical seals, I concede. The WP is easy to replace on the 720 engine. Keep it in mind if other efforts do not give the desired results.

I had a bad RR wheel brg on the '82 Wagon. It was bad when I got it at 86k, it grew worse but took about 30k miles before it was definite enough to know what it was and sound bad enough to replace. Some problems do not grow appreciably worse with time, and your WP leak (if it exists) could be one of them, because of the nature of the seal surface pressure provided by the spring versus ambient pressure conditions.

Or something like that.

_________________
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.


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Post Number:#12  PostPosted: Wed Apr 04, 2007 11:33 pm 
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asavage wrote:
Have you seen Luke lately? He's gotten old and fat like the rest of us.

The WP is easy to replace on the 720 engine. Keep it in mind if other efforts do not give the desired results.

I had a bad RR wheel brg on the '82 Wagon. It was bad when I got it at 86k, it grew worse but took about 30k miles before it was definite enough to know what it was and sound bad enough to replace.


yep, I guess the Force hasn't helped him much with the age or weight problem either, eh? Certainly hasn't helped me.

Nice to know it is easy to replace, thanks. But in my case (Jeep/radiator/fan shroud) it is a pain just to remove the fan clutch, the way mine is rigged up, which I think I need to do first (remove the clutch)? Probably easier for me to just start out by pulling the radiator first on mine like a did recently to get the top tank on it fixed, then I can get the fan shroud off, then the fan and then the clutch, oh and then the WP!.

On the wheel bearing, I hear the squeaky wheel gets the oil! It just has to get loud and annoying enough first! LOL.

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Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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Post Number:#13  PostPosted: Sat Apr 07, 2007 12:19 am 
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I replaced the overflow/return hose earlier today with a the proper rubber hose. No questions that hose is tight and sealed now. I will post am update after a few long highway trips.

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Regards,

Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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Post Number:#14  PostPosted: Sat Apr 07, 2007 1:13 am 
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Is it a crossflow radiator?? These are often designed to have an air gap. The air can collect in the engine so the radiator look full. If the engine is too high in the engine bay. In these type of cars the water pump would draw in the water from the catch tank on startup when the thermostats closed. The rely on you getting all the air out with special filler bottles and the car parked on an up hill slope.

Have a good look at heater core. Even plug the hoses. I dont think the JEEP will have a heater tap??, these are a common cause of this problem.

Also heat exchangers are like waterpumps as they seal with pressure.

The trouble with conversions is that other systems are not always compatible. It may be that the return bottle is too low, the newer models I work on have the return hose out of the bottom and its mounted in the top left rear corner. It syphons out when you remove the cap. The 4 liter 6cyl drops the water level in the tank when you rev it pressurising the engine.

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Post Number:#15  PostPosted: Sat Apr 07, 2007 7:55 pm 
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davehoos wrote:
Is it a crossflow radiator??

Ans: NO.

These are often designed to have an air gap. The air can collect in the engine so the radiator look full. If the engine is too high in the engine bay. In these type of cars the water pump would draw in the water from the catch tank on startup when the thermostats closed. The rely on you getting all the air out with special filler bottles and the car parked on an up hill slope.

Have a good look at heater core. Even plug the hoses. I dont think the JEEP will have a heater tap??, these are a common cause of this problem.

Ans: Has no heater core at this time. It is valved off at this time (custom) but has been used and had no effect on the problem.

Also heat exchangers are like waterpumps as they seal with pressure.

The trouble with conversions is that other systems are not always compatible.

Ans: That is not the problem in this case.

It may be that the return bottle is too low,

Ans: Not the case with this set up. It has actually worked on good days!

the newer models I work on have the return hose out of the bottom and its mounted in the top left rear corner. It syphons out when you remove the cap.

The 4 liter 6cyl drops the water level in the tank when you rev it pressurising the engine.


So does the SD-22 (at least mine does). This is not a 4.0 jeep engine(?), it is an SD-22 in a jeep with a jeep downflow radiator. Did I miss understand you?

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Mike

1985 Jeep Cherokee Pioneer, 2WD, retrofitted with SD-22 & 5 spd manual trans, a 4X4 Gas Wagoneer ltd. (XJ) Jeep, 4.0 L w/ AW4 auto, and now 2 spare 2wd Jeeps, 87 & 89.


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