Another 3.9 overheat question after 12 hours of searching past posts

[bradyarmstrong]

Hello all. Working on 2001 ls 3.9L. After an intermittent overheat issue I had mechanic pressure test system. He advised system was good and quoted 600 for a thermostat install. Decided to replace myself. Issue has come with the bleeding process: From the bleeding process linked in many forums here is where I started having issues. Refilled approx 1 gallon of 50/50 as stated, between engine fill and degas, and was following process fine until these steps.

11. Allow the engine to idle for five minutes, add coolant to the degas bottle as needed to maintain the cold fill MAX mark.

? Degas bottle never lowered so no coolant needed to be added. Seems odd to me

12. Reopen the heater air bleed to release any entrapped air and close again.

Immediately got stream of coolant, no air seemed to escape


On 3.9L engines

13. Maintain engine speed of 2,000 rpm for 3-5 minutes or until hot air comes from the heater.

within seconds of putting engine under a load of 2,000 rpm the temp gauge starts to sky rocket. quickly opened valve to see if air would escape and still got steady stream

I shut down the engine and allowed hours to cool, repeated the process two more time with exact same results.

Any tips would be appreciated as I have searched high and low on this great site to find a similar problem.

 

[LS4me]

Was the degas bottle replaced? The other plastic pieces around the thermostat housing?

This is the same as every other overheat problem. ALL plastic pieces must be replaced; unless you like getting frustrated, bleeding the system repeatedly and spending lots of cash on coolant......

 

[bradyarmstrong]

I have not replaced any plastic. Is a low milage car and I figured any leaks from plastic would have shown up in pressure test. My train of thought was that if there was air entering the system that I would be seeing it quite a bit in the bleeding process. It is not my vehicle so I was trying to save money where I could. Is definitely not my intention to waste time here. Sorry for inconvenience. Just thought that air in the system would be very noticeable during the bleeding process from bad plastics, hoses, ect.

 

[LS4me]

I have not replaced any plastic. Is a low milage car and I figured any leaks from plastic would have shown up in pressure test. My train of thought was that if there was air entering the system that I would be seeing it quite a bit in the bleeding process. It is not my vehicle so I was trying to save money where I could. Is definitely not my intention to waste time here. Sorry for inconvenience. Just thought that air in the system would be very noticeable during the bleeding process from bad plastics, hoses, ect.

Leaks never show up in pressure tests (noted many times in other threads) and plastic deteriorates over time. My wife's lowish (68K) mileage '06 sprung a leak at the thermostat housing a couple of weeks ago. The other threads will tell you exactly why the system lets in air.

 

[bradyarmstrong]

Thank you for your time. I guess what Im not understanding is why isn't the system just acting as an air pump when I try to bleed it? Im getting no air out at all during the bleeding process. only coolant. I would feel much more comfortable in replacing all of those parts at someone elses expense if I saw air coming from bleeder valve.

 

[LS4me]

You won't see air coming out. You should see coolant. That means the air is purged.

 

[bradyarmstrong]

so with air purged a cracked plastic will cause catostrophic temps after a 15 second load of 2,000 rpm. blows my mind. Guess plastic and hot liquid is just a recipe for problems. I will let my friend know. Thanks again.

 

[LS4me]

Actually..... Air leaks into the system through very, very tiny cracks in the plastic parts. The degas bottle/reservoir is one of the first culprits.

 

[bradyarmstrong]

well in a perfect world I would love to put the jag housing and a brand new degas in it for her but thats a lot of coin in one shot. Will just have to see what she says. And from what I've read the dorman degas is junk so I can't advise her to go that route.

 

[bradyarmstrong]

My other train of thought was that it had only overheated twice in two weeks and now that I have opened up the system it is overheating everytime that I am not bleeding it correctly. But in every post it tells to follow it to the letter but there is no sort of troubleshooting if you encounter a problem while bleeding. Thinking of draining the whole system and starting from scratch again,

 

[joegr]

Thank you for your time. I guess what Im not understanding is why isn't the system just acting as an air pump when I try to bleed it? Im getting no air out at all during the bleeding process. only coolant. I would feel much more comfortable in replacing all of those parts at someone elses expense if I saw air coming from bleeder valve.

The air bleed that you open is the heater air bleed. It has very little to do with the air trapped in the engine cooling loop. That air self bleeds at the degas bottle (that's why it's called degas). This of course, won't work if the degas bottle is defective. Usually, they are just cracked, but in your case it may also be that the internal air bleed pipe in the degas bottle has come loose.

There really are good, experience based, reasons that so many of us say in so many threads to replace all the plastic cooling system parts once you have a problem.

 

[1LoudLS]

but there is no sort of troubleshooting if you encounter a problem while bleeding.

this is not correct, the trouble shooting steps are simple, if you have problems with overheating OR any problems while bleeding. there are two steps that should be taken...

1) replace every single part that is made out of plastic and the thermostat in the cooling system

2) follow bleeding procedure again




most people screw up step one...

 

[Telco]

I realize that it doesn't make sense that all plastic needs to be replaced when one plastic item fails. This is not an issue on any other car but is a known problem on the LS. Just press the "I Believe" button and replace all the plastic. On my own car, I had a little tiny seeping leak on the top radiator hose on the molding break point. Based on advise from this forum I replaced all plastic. In addition to the seeping hose I found that the thermostat housing had disintegrated internally and the degas bottle was covered with cracks. None of this other damage was found until I replaced the cooling system parts.

If you plan to keep the car, may as well spring for the metal Jag parts too. At least you have that option, we Gen 2 owners do not have the option of replacing any parts with metal unless we want to have them made ourselves. The whole cooling system will need to be redone again in about 6-8 years and 100K miles, assuming the parts are even available then. I'd also advise the LS FanBoys (you know who you are) to go ahead and stock up on the cooling system parts. Otherwise you'll be forced to part with your car when the parts fail and can't be found at any price.

 

[joegr]

... This is not an issue on any other car but is a known problem on the LS. ...

Sadly, this is not a true statement. This is actually true on a growing number of cars these days. It is certainly true for BMW E46s. They go even further, as there are plastic pulleys and such that also have to be replaced. However, on the E46 you are taking a major gamble if you don't replace all the plastic every so often instead of waiting for something to start to fail. If a pulley goes, it may send the mechanical fan through the radiator. If the expansion take explodes (they explode instead of cracking), then the engine has no failsafe cooling and may be destroyed before you make it off the road...

 

[Telco]

Sadly, this is not a true statement. This is actually true on a growing number of cars these days. It is certainly true for BMW E46s. They go even further, as there are plastic pulleys and such that also have to be replaced. However, on the E46 you are taking a major gamble if you don't replace all the plastic every so often instead of waiting for something to start to fail. If a pulley goes, it may send the mechanical fan through the radiator. If the expansion take explodes (they explode instead of cracking), then the engine has no failsafe cooling and may be destroyed before you make it off the road...

Heh heh, I know you, amongst others here, are BMW fans but I am not and am proud to say I know little to nothing about the foibles of the BMW brand. This is surprising to hear though, because even though I don't like BMWs I thought they were supposed to be engineered for total reliability. This does not sound reliable. I think I'd replace that pulley setup with an electric fan and metal pulley, were it my car. No idea what to do about the exploding coolant tank, except maybe see if there is a General Motors tank that would fit. GM makes pressurized plastic tanks and they can last hundreds of thousands of miles. The one in my truck now has almost 300K miles on it now, still works fine.

 

[jgscott]

Dorman had a problem on the Degas bottle for all cars.

Replace the Degas bottle. Bleeding is NOT your problem. Air is getting in the system from a part malfunction like they are telling you & they told me. The lack of pressure will do exactl what you are saying its doing. The Degas leak will not show up on a pressure test, strange at it seems. Even a low miles 2001 has 13-14 year old coolant parts on it.

 

[joegr]

Heh heh, I know you, amongst others here, are BMW fans ...

I have a BMW, but I am not a BMW fan (nor a hater, I'm neutral on it). Anyway, it's not just BMW...

 

[Blueberryyum02]

It's not that all plastic coolant parts go bad at once, it is advised to just replace all of it at one time, to save yourself the headache of going in and changing parts one by one, I have a 2002 Lincoln ls wit over 200 thousand miles on it,
my situation began when i changed the engine fill cap, a week later I changed the upper radiator hose cause it was leaking at the T fitting, I thought OK fine there's no need to take these guys advice on replacing all the plastic coolant parts.

Just fix what needs to be fixed and be done with it, boy was I wrong, once the pressure hit 16 psi I found white residue just about every where, so here I am ordering parts left and right to stay ahead of it, mind you this is my daily driver, so these things are being done on a day to day basis as the parts come in and on my days off, to save dollar cause the shops was about to take me on the ride of my life for a nice piece of change

after replacing all plastic coolant parts including the degas bottle I ran into a no heat situation,

Had to go back in and change the water pump cause with this new pressure it failed, at the plastic rim where the rubber O ring goes, replaced it just to find out that the DCCV, took a crap on me.

I Replaced it just to find out, that my radiator had a leak. And at the end of the year the last part to replace is, the heater pump, when they say replace all plastic at the same time trust me, and the guys of LVC


PRESSURE WILL BUST A PLASTIC PIPE.
ON THE LS

My advice would be to shop around on rock auto they having a close out sale on ls parts
Try Tasca parts and others to find the deals.

And check the hose clamps cause I just found out yesterday morning, that I have been driving for some months with the clamp on the T fitting hose that feeds the DCCV in the open position, and the only sign was a white residue. No over heat the degas bottle stay at the same level and heat would blow while driving and at idle.

 

[bradyarmstrong]

Well last weekend I managed to change the degas bottle. Bled the system and it ran fine all week. Still waiting on the rest of the parts. But yesterday on a five minute drive the gauge went from normal to pegged out in about 2 seconds flat. Got car pulled over and opened hood. Degas cap was ambient temp. Restarted car and temp gauge went strait to normal operating temp. I don't think that if the car was really pegged out that it could have cooled in under four minutes. Does this sound like a cylinder head temp sensor to anyone else? Suppose I'll change that while I wait on the rest of the parts. It is the gfs daily driver so trying to keep it running till the weekend when I can do the overhaul on the plastics. It was a cylinder temp sensor code tripped in the obd2 that started everything, but didn't know if they would be intermittent like that.

 

[joegr]

Lots of threads on here say the same thing. Almost all of them end with there being trapped air in the cooling system, due to cracked plastic. A lot of people don't want to believe this because of how the gauge operates. It is very non-linear. It stays at dead center of the scale up to a fairly high temperature. (It is already overheating while still at dead center.) Once it passes a threshold, it very quickly moves to full scale.

I do recall one thread where it was a nicked wire going to the CHT that was shorting under the manifold.

The degas bottle gets very little coolant circulation, so it does tend to remain cooler than the rest of the system. If you have leaks in the system, then the degas may get no circulation, and may remain cold like you described.

 

[FDR]

To add a little bit of explanation, the reason why air leaking causes overheating without coolant leaking out is the same reason you need a pressure cooker at high altitudes. The higher the pressure, the higher the boiling point. At high altitude, the lower air pressure causes water to boil at too low of a temperature, so it doesn't cook your food. The cooling system is pressurized. When it loses it's pressure, the coolant boils in the lines, and does an absolutely poor job of transferring heat. You can hold your hand in 300 degree heat a lot longer than you can hold it in 300 degree water.