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Most of us are familiar with some versions of head gasket leaks. I recently discovered one odd version which was a single gasket leak only between cylinders #4 and #5, with no loss of oil or coolant, and no oil or air in the coolant, no coolant in the oil and a perfectly normally exhaust, no oil or coolant in the exhaust. Even the spark plugs look normal. The only clue was 25 psi compression and on those 2 cylinders and a rough idle with no other possible cause except for low compression for the rough idle.
Now onto another engine with an odd issue and my question! In my Nissan diesel engine, I have had an odd, intermitent problem with some air getting into my coolant system, sometimes, but not always, and it is an open system by the way. I have had the problem for years, and probably 25,000 miles now, and it is getting worse lately. The most prevalent part of the problem is that frequently, like 50% of the time, or sometimes 25% of the time, the coolant in the overflow recovery bottle will fail to return to the radiator when it cools down overnight. Sometimes, if I release the air pressure from the top of the radiator through the cap to the overflow bottle at the end of the day, before the coolant cools down, the radiator will draw all the coolant back in from the overflow bottle, but not always, and not always all of it, sometimes just half of it returns.
I have checked and serviced all the other possible gremlins except for a possible intermitent very odd head gasket leak, or a coolant pump with a seal that sucks air at certain times, and then seals at other times, but does not leak out coolant under pressure, and never leaked coolant out when cold, until possibly a few weeks ago. I say the water pump seal never leaked out coolant until possibly a few weeks ago, because I had a small over night leak sitting in the driveway overnight, during an overnight cold front recently, where there was a small puddle under the harmonic balancer which could have been from the water pump seal, but I could not verify the true source.
Recently, air, foam in the radiator has gotten worse when running the engine, but it has been bad 2 out of the last 14 days, bad one day, ok for the next 6 days. I ran a pressure check on the radaitor last week, replaced the radiator cap with a presure test / pump rig, and it sat at 7 lbs of pressure for 20 minutes, and 1/4 throttle in park, with no change in the radiator coolant system pressure. In fact we had to pump the pressure up from about 4 psi to 7 psi. It has a 165 F thermostat, an runs cool until it gets loaded on the freeway, or has the A/C on during a very hot day, and this test was A/C off, at about 50 F that day. Oh, and to top off the madness of this phenomenon, it never looses any coolant!!!! :banghead:
So that is the back ground, now the question is, has anyone else ever seen a water (coolant) pump suck air periodically, engine on and or off, pump rotating, or pump not rotating and cooling down, with out ever leaking coolant externally at the water pump seal?
Has anyone ever seen a really ODD head gasket leak that did not ever over heat the cooling system, that allowed air into the cooling system during cooldown, and did not overpressure the cooling system with compression air, never lost any coolant for months and even years, yet when the coolant cools down it let air into the coolant system instead of drawing coolant back in from the overflow bottle? Or it let some air in to the coolant system, and displaced some coolant, like once a wek, then stopped for a week, and when it did let air into the coolant system it did not overpresure the system or overheat it?
I know a lot of XJ'rs with the old closed coolant system have had air in the system problems, could their problem be like mine (at least what I think mine is) namely the water pump seal sucking air in on rare occasions.
I am also wondering, beyond just a failing water pump seal and early warning signs, if the engine start up, or thermostat cycling could not be involved in a pulse effect that temporarily opens the seal allowing air to be sucked in, in combination with a weak, old spring in the seal. I have actually seen this on large self priming industrial pump seals. They would suck dry junk into the seal face on a mechanical seal in the first second of pump start up on self primmg pumps that did not have an external seal water flush. The stuff they sucked in would hold the seal face open and the pump would start leaking externally big time.
I am getting ready to replace my intake & exhaust manifold gaskets in order to service the exhaust down pipe flange, and to replace the water pump since I believe the problem is the water pump seal, but I want to make sure I am not overlooking another possible source of the mysterious air in the coolant system!
I suspect the one time, recent coolant puddle under the harmonic balance, which is under the water pump seal area on my engine, that happend on the coldest day of the year here about 2 weeks ago was my confirmation. Also keep in mind my engine is 22:1 ratio diesel diesel, not an 4.0 gasser, and the engine is not overheating, not loosing coolant, and the engine runs like it was brand new.
Looking for opinions and alternative posibilities and ideas, and offering this odd water pump seal sucking leak as an alternative to some XJ-4.0 air in the system problems reported by many others with the older closed systems.
Lastly, the idea of the water pump seal sucking air was offered to me by a nearly retired lifetime diesel engine mechanic who says he has seen it before.
I just don't want to replace the pump and find out a week later its some 1 in a billion very odd type of head gasket leak right after doing the manifold gaskets and water pump replacement. I hate :smsoap:doing the same stuff twice in the same year.
:helpme:
Now onto another engine with an odd issue and my question! In my Nissan diesel engine, I have had an odd, intermitent problem with some air getting into my coolant system, sometimes, but not always, and it is an open system by the way. I have had the problem for years, and probably 25,000 miles now, and it is getting worse lately. The most prevalent part of the problem is that frequently, like 50% of the time, or sometimes 25% of the time, the coolant in the overflow recovery bottle will fail to return to the radiator when it cools down overnight. Sometimes, if I release the air pressure from the top of the radiator through the cap to the overflow bottle at the end of the day, before the coolant cools down, the radiator will draw all the coolant back in from the overflow bottle, but not always, and not always all of it, sometimes just half of it returns.
I have checked and serviced all the other possible gremlins except for a possible intermitent very odd head gasket leak, or a coolant pump with a seal that sucks air at certain times, and then seals at other times, but does not leak out coolant under pressure, and never leaked coolant out when cold, until possibly a few weeks ago. I say the water pump seal never leaked out coolant until possibly a few weeks ago, because I had a small over night leak sitting in the driveway overnight, during an overnight cold front recently, where there was a small puddle under the harmonic balancer which could have been from the water pump seal, but I could not verify the true source.
Recently, air, foam in the radiator has gotten worse when running the engine, but it has been bad 2 out of the last 14 days, bad one day, ok for the next 6 days. I ran a pressure check on the radaitor last week, replaced the radiator cap with a presure test / pump rig, and it sat at 7 lbs of pressure for 20 minutes, and 1/4 throttle in park, with no change in the radiator coolant system pressure. In fact we had to pump the pressure up from about 4 psi to 7 psi. It has a 165 F thermostat, an runs cool until it gets loaded on the freeway, or has the A/C on during a very hot day, and this test was A/C off, at about 50 F that day. Oh, and to top off the madness of this phenomenon, it never looses any coolant!!!! :banghead:
So that is the back ground, now the question is, has anyone else ever seen a water (coolant) pump suck air periodically, engine on and or off, pump rotating, or pump not rotating and cooling down, with out ever leaking coolant externally at the water pump seal?
Has anyone ever seen a really ODD head gasket leak that did not ever over heat the cooling system, that allowed air into the cooling system during cooldown, and did not overpressure the cooling system with compression air, never lost any coolant for months and even years, yet when the coolant cools down it let air into the coolant system instead of drawing coolant back in from the overflow bottle? Or it let some air in to the coolant system, and displaced some coolant, like once a wek, then stopped for a week, and when it did let air into the coolant system it did not overpresure the system or overheat it?
I know a lot of XJ'rs with the old closed coolant system have had air in the system problems, could their problem be like mine (at least what I think mine is) namely the water pump seal sucking air in on rare occasions.
I am also wondering, beyond just a failing water pump seal and early warning signs, if the engine start up, or thermostat cycling could not be involved in a pulse effect that temporarily opens the seal allowing air to be sucked in, in combination with a weak, old spring in the seal. I have actually seen this on large self priming industrial pump seals. They would suck dry junk into the seal face on a mechanical seal in the first second of pump start up on self primmg pumps that did not have an external seal water flush. The stuff they sucked in would hold the seal face open and the pump would start leaking externally big time.
I am getting ready to replace my intake & exhaust manifold gaskets in order to service the exhaust down pipe flange, and to replace the water pump since I believe the problem is the water pump seal, but I want to make sure I am not overlooking another possible source of the mysterious air in the coolant system!
I suspect the one time, recent coolant puddle under the harmonic balance, which is under the water pump seal area on my engine, that happend on the coldest day of the year here about 2 weeks ago was my confirmation. Also keep in mind my engine is 22:1 ratio diesel diesel, not an 4.0 gasser, and the engine is not overheating, not loosing coolant, and the engine runs like it was brand new.
Looking for opinions and alternative posibilities and ideas, and offering this odd water pump seal sucking leak as an alternative to some XJ-4.0 air in the system problems reported by many others with the older closed systems.
Lastly, the idea of the water pump seal sucking air was offered to me by a nearly retired lifetime diesel engine mechanic who says he has seen it before.
I just don't want to replace the pump and find out a week later its some 1 in a billion very odd type of head gasket leak right after doing the manifold gaskets and water pump replacement. I hate :smsoap:doing the same stuff twice in the same year.
:helpme:
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