Engine Running Cool - Code P0128

[Pearl'06'LS]

Hi all

I own a 2006 Lincoln LS V8 for 10 years now. It has 210,000 kms.

So I noticed a couple weeks ago my engine temp gauge was just a touch under the normal position it usually is at, indicating the engine temp is below norm. Then, a few days ago my engine light came on and I pulled the code P0128.

I'll start by saying, last spring (approx 10,000km ago) I replaced the DCCV. I am certain I bled the system properly following the steps posted here on this site (thank you). I drove all last summer and parts of the winter with no issues and the temp gauge was where it's supposed to be, right at 9 o'clock.

Now, once the engine is nice and warm after driving 30 mins it sits just under 9 o'clock. I'm not really noticing any loss of power, but I do notice the heat is not as hot but it still gets pretty warm/hot.

I've checked the coolant level (good), re-bled the system (good), checked to make sure the fan isn't constantly running (good).

I have not checked the thermostat although I pulled the fill cap off to look at it on a cold engine. It's hard to see it properly while installed, I squeezed the upper rad hose on the passenger side and had fluid come back to me through the fill hole. Would this indicate the thermostat is open? Should it not be closed on a cold engine and only opening once it reaches proper temps? The upper rad hose mentioned leads to the back side of the thermostat, so my thoughts are it should not allow fluid to pass through unless the thermostat is open?

Also, if I do pull of the existing thermostat, is it possible to test these in boiling water as it comes already in the housing? I know if I pull it off and its already open then the answer is simple, but if its closed I would like to test it. I do have a laser temp gun to monitor the temps properly. I'm a little hesitant to just go buy a new thermostat as its about $70 CAD.

I have not checked the Coolant Temp Sensor or the Intake Air Temp Sensor.

Has anyone had issues with the thermostat in the past, if so how was it acting?

I've searched these forums for thermostat issues but have only found 'overheating' issues and nothing for 'engine running cool' issues.

Thanks in advance for any help or advice!

 

[joegr]

When you squeeze the hose, coolant will move out the engine fill (if the cap is off) whether the thermostat is open or closed, so that doesn't really diagnose anything. That said, I can be pretty confident about what has happened. It's probably not the thermostat itself, so much as it is the plastic parts that it sits in. The plastic ears that hold the thermostat together may have broken off, and/or the plastic in the crossover tube that separates the different coolant flows has disintegrated. (The odds are good that it is both.)
Experience has proven that once you have one plastic failure, the rest is very close behind. You really need to do everything in the post linked below (sorry).

GenII LS8 Cooling System Overhaul

 

[Pearl'06'LS]

When you squeeze the hose, coolant will move out the engine fill (if the cap is off) whether the thermostat is open or closed, so that doesn't really diagnose anything. That said, I can be pretty confident about what has happened. It's probably not the thermostat itself, so much as it is the plastic parts that it sits in. The plastic ears that hold the thermostat together may have broken off, and/or the plastic in the crossover tube that separates the different coolant flows has disintegrated. (The odds are good that it is both.)
Experience has proven that once you have one plastic failure, the rest is very close behind. You really need to do everything in the post linked below (sorry).

GenII LS8 Cooling System Overhaul

I was afraid you would say that

I guess I'll start this evening by taking off the thermostat to see what I find. I don't have a lot of free cash right now so I will be a bit hesitant to start on a full cooling system makeover. With any luck the plastic parts will hold up for a little while longer.. that being said I will replace whats needed.

Once I get this t-stat apart this evening I'll check back with my findings!

Thanks again Joegr!

 

[1LoudLS]

you will be extremely lucky if other parts don't break just from you handling them, many of mine did.

 

[Pearl'06'LS]

So I haven't tried to fix this issue yet as time has not allowed, the car has been parked since the engine light came on. I appreciate the input here fella's. I will have time in the coming days to tackle this, I may try one last time to bleed the system again but am thinking it won't make any difference.

A question for the experienced guys: Being that I have somewhat recently replaced my DCCV there may be a possibility that I did not bleed the system properly (although I'm sure I did and put lots of km's on since the repair). That being said, if there was air still in my cooling system wouldn't that cause an overheating issue and not an overcooling issue? I would only think this may cause false readings and show overcooling if the coolant temp sensor is not submerged in coolant, but that would also mean a fair sized air bubble and would most likely cause it to overheat?

I am just trying to make sure I'm on the right trail before I go and order a couple hundred dollars worth of plastic parts along with the t-stat. I do realize many of you have had these type of issues before and it all traces back to these plastic parts failing, but it also seems to all be related to overheating and not overcooling.

I have thought about your reply Joe, and pulled the fill cap off above the t-stat. I reached in with a screwdriver to see if the t-stat had any movement which it did not.. possibly indicating that it is still properly intact? Another thought I had was if there was a failure on the plastic tube inside that separates flows has failed, this would cause channeling of fluid and disrupt the proper flows.. which may cause overcooling. I do realize the only way to verify is to take it apart for inspection, and while I'm doing that I may as well replace it for time has shown its just a matter of time anyway before it fails.

Maybe I am just thinking out loud here!? LOL

Also, has anyone had any experience with the aftermarket (Dorman or others) parts.. are they comparable to the OEM parts? Mainly is the plastic as beefy on aftermarket as it is on the OEM?

Ebay has quite a bit, and with the info you fine people have provided it should be fairly easy to make sure I get the right parts. I see some kits available as well, but none come with that elbow leading to the intake manifold... is this elbow a must to replace? My luck I won't change it and it'll fail in a few weeks!

Thanks again for your time, I very much appreciate it!

 

[joegr]

Dorman = bad.
Air = overheat, not overcool.
I think that the PCM is looking at the CHT for the too cold warnings, so an air pocket shouldn't cause that to read lower than real.

 

[Pearl'06'LS]

Dorman = bad.
Air = overheat, not overcool.
I think that the PCM is looking at the CHT for the too cold warnings, so an air pocket shouldn't cause that to read lower than real.

Understood, I see why you refer to the T-Stat housing and plastic parts. If those plastic pieces have deteriorated on the interior as you mentioned, then fluid channeling will most likely happen causing who knows what issues.

I'll start putting my parts list together, I'm not sure I'll go as far as replacing everything but I'll be sure to do the main stuff all around the thermostat. I may do the elbow leading under the intake manifold, as 1LoudLS mentioned about crumbling.. why take the chance for another $100. I've read through the other posts about the 2 back bolts for this elbow, very helpful stuff!

I really hope once I take it apart the problem reveals itself.

Thanks again for your advice, I'll let you know what happens.

 

[grizzlyls]

You can save a little money by looking into the Jaguar comparable listings. You will find Uro parts there. I found that my Uro degas bottle was a little beefier feeling/looking than the OEM, but be aware my mechanic that put it in said he had to mod the firewall tab a bit - which is probably why Uro doesnt outright list it for a Lincoln. hose/plastic combos can be had cheaper from reputable manufacturers too.

 

[Pearl'06'LS]

You can save a little money by looking into the Jaguar comparable listings. You will find Uro parts there. I found that my Uro degas bottle was a little beefier feeling/looking than the OEM, but be aware my mechanic that put it in said he had to mod the firewall tab a bit - which is probably why Uro doesnt outright list it for a Lincoln. hose/plastic combos can be had cheaper from reputable manufacturers too.

Thanks Grizzlyls, I'll surely look into that option!

 

[Pearl'06'LS]

Ok I've gone ahead and ordered these parts, I will be replacing the thermostat and its housing, and the main plastic body it attaches to along with all gaskets in between (4 gaskets in total). Altogether I`ll be paying $220 CAD. Pretty good deal I guess for all OEM parts.

I've opted out of replacing the elbow leading under the intake manifold for now, if need be I can get the part 3 mins down the road from the dealership along with the other gasket and bolts it needs for another $100. I`m also opting out of doing the degas bottle right now and other hoses.

I`ve also noticed that now the weather is warmer it will get up to temp but it still takes longer then it should and will only do so with the heater off. Once I turn on the heater with in a minute or so the temp will drop slightly.

Fingers crossed this solves my overcooling issue. Once I get the t-stat and its housing and the main body off I really hope to see a problem inside of it.

Thanks again for your help Joe, as always!

 

[AmsterDutch]

Ok I've gone ahead and ordered these parts, I will be replacing the thermostat and its housing, and the main plastic body it attaches to along with all gaskets in between (4 gaskets in total). Altogether I`ll be paying $220 CAD. Pretty good deal I guess for all OEM parts.

I've opted out of replacing the elbow leading under the intake manifold for now, if need be I can get the part 3 mins down the road from the dealership along with the other gasket and bolts it needs for another $100. I`m also opting out of doing the degas bottle right now and other hoses.

I`ve also noticed that now the weather is warmer it will get up to temp but it still takes longer then it should and will only do so with the heater off. Once I turn on the heater with in a minute or so the temp will drop slightly.

Fingers crossed this solves my overcooling issue. Once I get the t-stat and its housing and the main body off I really hope to see a problem inside of it.

Thanks again for your help Joe, as always!

You're not hurting anything by replacing those plastic parts...the plastic is deteriorating by the day so chalk this up to maintenance ...just my 2 cents though ....personally I would've started with changing out the thermostat first... many ppl will disagree with me but when it comes to cars Starting with the basics are always the best

 

[joegr]

You are going to regret not replacing that elbow. You'll be replacing the degas bottle and upper radiator hose a few days later, but at least there all you will have lost is the cost of coolant. For that elbow, you'll be doing all the work you did to replace the other parts all over again.
It's okay, most have to learn it this way.

 

[1LoudLS]

....personally I would've started with changing out the thermostat first... many ppl will disagree with me but when it comes to cars Starting with the basics are always the best

the reason most people will disagree with you is because when you buy the thermostat only and go to change it out, once you begin to take it apart and the parts to the thermostat (since the one in this car is not just one part and instead is many parts that are held together by the T-stat housing itself) shoot all over the place and the housing you are holding crumbles to dust, then you will be waiting longer to get more parts in. I guess as long as you have a second car then it wont be that bad, but if that car is your only transportation, then you might screw yourself.

add to that, anybody that has been on here for a couple of years or more has seen many many cooling system problems threads and I don't think a single one of them has ever been due to a failed T-stat.

 

[AmsterDutch]

the reason most people will disagree with you is because when you buy the thermostat only and go to change it out, once you begin to take it apart and the parts to the thermostat (since the one in this car is not just one part and instead is many parts that are held together by the T-stat housing itself) shoot all over the place and the housing you are holding crumbles to dust, then you will be waiting longer to get more parts in. I guess as long as you have a second car then it wont be that bad, but if that car is your only transportation, then you might screw yourself.

add to that, anybody that has been on here for a couple of years or more has seen many many cooling system problems threads and I don't think a single one of them has ever been due to a failed T-stat.

I'm just talking from my experience with a 2001 Lincoln LS I had two plastic coolant parts start turning a brownish color on me ...the car wasn't over heating But when the T-stat and other piece started changing colors I knew I needed to take action so I replaced the T-Stat housing with a Euro aluminum and the other part ASAP I didn't change the degas bottle or any other parts and that was about a year ago, my car is running great with no leaks I even kept the same thermostat ...properly bled the car after changing out parts which is of most importance.... when the next problem comes I'll fix it ...Every car situation isn't the same and then again some are ...not discrediting the guys that have been on here for years....I just do things differently when it comes to my LS

 

[joegr]

You do realize that the gen II thermostat and crossover are nothing like your gen I, which has a normal thermostat?

 

[AmsterDutch]

You do realize that the gen II thermostat and crossover are nothing like your gen I, which has a normal thermostat?

I wasn't aware that they were so different ...I'm still learning so much about the Gen 1 that I haven't even begun to do research on the Gen 2 ...I'm starting to think that with some of the changes done on 2nd Gens I might stay away from buying one...yes I understand that they improved the timing chain but the cooling system ( rolling eyes ) this looks like a mess

 

[AmsterDutch]

You do realize that the gen II thermostat and crossover are nothing like your gen I, which has a normal thermostat?

Hopefully Pearl06'LS has been reading all these posts and now sees the importance of changing out ALL THE COOLANT PARTS ON THE Gen II Lincoln LS because I was wrong and I admit it ...the Gen 1 is totally different than the Gen 2 ...you'll save much work and headaches doing all the coolant parts all at once on Gen 2

 

[1LoudLS]

I'm starting to think that with some of the changes done on 2nd Gens I might stay away from buying one...

lol, after owning both gens, there is no way that I would ever consider buying another 1st gen... too many things would annoy me that were fixed with the 2nd gen.

yes I understand that they improved the timing chain but the cooling system ( rolling eyes ) this looks like a mess

so you would rather have a known problem where if/when it goes bad it can destroy your engine and the repair requires removing all of the coolant parts then the front of the motor vs a problem where the car will likely just overheat and only requires you to just replace a bunch of plastic parts once in the life of the car? thats odd logic.

 

[AmsterDutch]

lol, after owning both gens, there is no way that I would ever consider buying another 1st gen... too many things would annoy me that were fixed with the 2nd gen.




so you would rather have a known problem where if/when it goes bad it can destroy your engine and the repair requires removing all of the coolant parts then the front of the motor vs a problem where the car will likely just overheat and only requires you to just replace a bunch of plastic parts once in the life of the car? thats odd logic.

So what I hear you saying is my timing chain is going to destroy my engine or are you saying it MIGHT DESTROY MY ENGINE ...this is getting ridiculous to say the very least...the world I live in works like this ...if you're good to your car and do proper maintenance then your car will last a long time ( rolling eyes once again )

 

[AmsterDutch]

lol, after owning both gens, there is no way that I would ever consider buying another 1st gen... too many things would annoy me that were fixed with the 2nd gen.




so you would rather have a known problem where if/when it goes bad it can destroy your engine and the repair requires removing all of the coolant parts then the front of the motor vs a problem where the car will likely just overheat and only requires you to just replace a bunch of plastic parts once in the life of the car? thats odd logic.

Once last comment before I'm done with this conversation ....besides the convenient yet poorly designed plastic quick connectors on fuel pump assembly module and having to replace plastic T-stat housing ...should I add some suspension components after 17 years on the road and a good clean tune up I've had no issues with my Gen 1 which I purchased for $1000 she is a smooth riding luxury sports car...maybe I'm just really lucky and my car wasn't built on a Friday...whatever the case I've had a lot more issues with other American made cars than the 2001 Lincoln LS ...

 

[Pearl'06'LS]

Hey guys, thanks for all the input.

So upon further consideration I’ve decided to replace the elbow as well.

I’m in the midst of doing the repairs and upon inspection of the t-stat housing I’ve noticed a crack in the centre where the needle comes into. I’m not finished the repairs yet but I’m fairly confident this could be the culprit to my sleepless nights.

 

[Pearl'06'LS]

So I’m pretty sure the problem is solved. I’ve had it running for a good hour now. It warmed up perfectly as I cycled through the heat/ac and bled the air out. I let it idle for a good hour while doing this with no issues then took it for a spin and everything seems fine.

The temp gauge now goes right to where it should and stays there no matter which actions are performed with the heater.

I’ll just monitor now to make sure nothing leaks and also the coolant level.

Thanks again Joe and everyone else who helps here.

Here’s another pic of that tstat housing, i found more cracks inside of it around where that pin or needle sits into. The inside piece is kinda mashed into it a bit too compared to the new part.