3.0 V6 ES9J Engine temperature control problem. (In a 407 Coupe with 116k on the clock) Help needed.

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Prrrgo

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Hiya folks.
Firstly I have a bit of experience with Peugeots as well as the ES9J engine - which I love, and I have Diagbox and have scanned and tested all components that are accessible. No faults. . This is a low k manual coupe that I just picked up. This problem has me stumped, so I'm reaching out for some help.

Here's what happens:
From cold the car will slowly come up to temperature (90C) at idle. On the road at highway speed it drops to and sits at 70 degrees C.. In stationary traffic it rises to 90 degrees C. Never any hotter. Then it goes back to 70 degrees C as I drive. At idle in the shed it comes up to 90 degrees C then the fans click in. It stays stable at 90C.
My guess was thermostat.
I pulled the thermostat (a bit of a task!), and while it is not quite closed at room temp, it opens when I boil it and closes when I cool it. Sparesbox supplied the wrong replacement thermostat so I put the old one back in. No change.
I have un plugged/ cleaned and reconnected all the sensors around the thermostat /coolant manifold.
The coolant hoses are all hot to touch (ouch!)
I have drained and flushed the coolant. The interior heater give out heat fairly consistently as far as I can tell.
I'm at a loss! Is there another thermostat somewhere else on the engine or what else could it possibly be?
Thanks for reading, I hope you can help.
 
Sounds like it is working as it should, just a little slow to come up to operating temperature. Replacing the thermostat should fix that.
 
Don't forget to replace the gasket or sealing ring (#8 in the diagram) as well as the thermostat. Unfortunately they are much harder to find than the actual thermostat.


Alvadi claims to be able to get them, but I've never tested them on supplying "Original spare parts" that they don't have in stock.

Suggest shopping at Spareto or Alvadi in Estonia instead of Sparesbox - you are more likely to get the right part. Use catcar.info or catalogs.ssg.asia to get part numbers.

BTW - well done on actually accessing the thermostat! I looked at changing the one on my XM (ES9J4), but decided that I would have to remove so much (potentially old & brittle parts) that I decided to leave it until there is some issue (such as you have) that indicates a problem.
 
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Actually, on thinking about it, the seal thingy is very likely the problem. This thermostat operates differently to the traditional units, in that instead of remaining fixed in one place (with just the centre opening & shutting), the whole thermostat moves in & out through the sealing ring. So it can jam open, half-open, or closed.

Here is a link to a page (from a lengthy thread) where it is all explained:

And since it requires a login, here is an excerpt:

Re: Simon's new Xantia V6 blog​


Post by xantia_v6 » 24 Jan 2017, 12:39


You can't run an ES9 with the thermostat removed. it is a bypass thermostat, so with it removed, the coolant will mostly bypass the radiator.

The ES9 thermostat has a piston which slides through a rubber seal to adjust the flow direction. Perhaps the sealant is causing the piston to stick to the seal?

I think that you might be better off without the sealant and with a leaking matrix.

The thermostat and seal are 4 and 8 in the top diagram.

Image


I can't for the life of me understand why the sealing rings are not either supplied with the thermostat, or are not at least equally available.
 
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Thanks All for your guidance.
Dacia - yes, the fan thermos cut in and out, and vary speed as they should.
Armidillo - There are two types of thermostats, one has a built in sealing gasket - which its the one I am now sourcing.
1696919066686.png
Part #s fromssg.asia is a great suggestion, thanks. There is a good guide on 406coupeclub.org which will help. Be careful to remove and re-fit the "push-in" hose joint into the head behind the thermostat housing at the same time as you remove and re-fit the thermostat and housing back onto the head.
Col, I'm going to replace the thermostat, but why at cruising speed does it drop to 70C, (so I guess stuck open) but when I boil it in a saucepan, it opens then closes when it gets cool?? It's got me tossed.
 
Prrrgo said:
Thanks All for your guidance.
Dacia - yes, the fan thermos cut in and out, and vary speed as they should.
Armidillo - There are two types of thermostats, one has a built in sealing gasket - which its the one I am now sourcing.
View attachment 228570
Part #s fromssg.asia is a great suggestion, thanks. There is a good guide on 406coupeclub.org which will help. Be careful to remove and re-fit the "push-in" hose joint into the head behind the thermostat housing at the same time as you remove and re-fit the thermostat and housing back onto the head.
Col, I'm going to replace the thermostat, but why at cruising speed does it drop to 70C, (so I guess stuck open) but when I boil it in a saucepan, it opens then closes when it gets cool?? It's got me tossed.
Click to expand...
See my 2nd post just above yours. If still in doubt, contact pugrambo on this forum, as he is a mechanic and understands how these work.

From your supplied picture, your new thermostat does NOT include the separate sealing ring I am on about. It has a separate part #, 134042 - you can see it clearly in the diagram supplied above.
 
Here's a couple of photos of the thermostat and sealing ring that I have.
Thermostat & sealing ring.jpg


Sealing ring fitted to thermostat.jpg



I think a little silicon grease may be a good investment to ensure that the thermostat moves smoothly through the ring. The ring of course seats into the housing, and should not move.

I still don't have the faintest idea where you will find one of these pieces of unobtanium...
 
Hi Prrrgo I am not entirely sure why you are concerned but here is a suggestion for an alternative reason for the temp drop. There may be some malfunction in the interior heater system that is taking enough heat from the coolant to drop the engine temperature below thermostat closed temp. I am not familiar with the system on the 406 but if it has climate control the air conditioner could possibly cover up a modest heat input to the interior. Just a suggestion for checking !
I suppose you have calibrated the temperature device you are using to measure it. Cheap hand held no-contact units can work OK and could be checked on a pot full of water on the stove and a real thermometer.
Jaahn
 
Just to follow this through, and thank you Armidillo for the thorough guidance,
I've sourced the correct thermostat 1338 73 and the (unobtanium) thermostat sliding seal 1340 42 and the two seals for the head to head transfer pipe 1340 46 From European Auto Imports in Box Hill, Melbourne. They do not stock the O ring 1208 15 but that is just an O ring so I should be able to pick up a matching one locally.
I'll let you know how I go once the parts arrive. Fingers crossed that this will solve the problem!
 
jaahn said:
Hi Prrrgo I am not entirely sure why you are concerned but here is a suggestion for an alternative reason for the temp drop. There may be some malfunction in the interior heater system that is taking enough heat from the coolant to drop the engine temperature below thermostat closed temp. I am not familiar with the system on the 406 but if it has climate control the air conditioner could possibly cover up a modest heat input to the interior. Just a suggestion for checking !
I suppose you have calibrated the temperature device you are using to measure it. Cheap hand held no-contact units can work OK and could be checked on a pot full of water on the stove and a real thermometer.
Jaahn
Click to expand...
Thanks Jaahn. If I have to go down this path, is it a console out job, or simple access to the sides of the interior heating system? I am getting no fault codes showing up on DiagBox PP
 
A comment Prrrgo.
I have no familiarity with a 406 so you would have to ask on the Pug forum probably. ;)

BUT the diagnostic system and the ECU (and other CUs) only register problems that are picked up electrically, either direct readings or effects that give electrical signal changes. THAT IS ALL YOU GET. Same with all car types. The heater has few electrical sensors on the water flow.

For example; if you are driving down the road and a wheel falls off it will not trigger any codes or errors unless the brake sensor or some electrical wire is damaged. The poor old driver will have to work out for himself why the car became undrivable-able !
Possibly need to get out and look instead of reaching for the code reader !:mallet: A lot of people, including young mechanics, have an over reliance on the data from "the port". They do not check the normal things or use their brain and training they were given.

For example; codes might say there is a miss in No3. Wow what to do next. You could pull the plugs out to find the tip fell off that plug. Probably did not need the reader if you did normal service on a well used engine. Just saying :rolleyes:
Jaahn
 
Good on you Jaahn, sticking up for a bit more common sense in this world.
By the way, I had a wheel fall off a 205 GTi once, which is a longer story for another time perhaps, but that definitely wasn’t caused by a miss in No3! 😊
 
There is no control valve for fluid flow through the heater on a 406. The heater receives full coolant flow all of the time.

It is not unusual for these engines to run cold. Typically on a run they will sit on about 70 degrees, creeping up at slower speeds, higher loads (including AC use) or warmer weather. This is because they are essentially a very efficient engine, and the cooling effect provided by the heater system, engine bay plumbing as well as the bleed hole through the thermostat is enough to keep the engine below the thermostat temperature.

If it gets past about 90 degrees, there may be a problem, and if it runs any cooler than 70 degrees on a run you may have a problem.
 
Thanks Demannu.
Perhaps I should have mentioned it, although I did in the Header to my query that it’s a 407 not a 406, but that doesn’t matter, I guess the coolant system is quite similar if not the same. It’s the ES9J 3.0 V6 petrol engine. I’m right now refitting the new thermostat and seals and will then do the factory coolant bleed and see how it goes.
Demannu, I’ve had a few of these, and never seen one run at 70C on the highway.
90C once the engine is warm always.
It will be a little while before I report on progress as the AC compressor is also being replaced and I’m still chasing one.
Any clues there for sourcing a replacement? It’s the clutch/coil that’s gone. Pump internals all ok and it was full of gas so no leaks. I’m in Ballarat Victoria
 
When you pulled the thermostat out did it come out easy or did you have to pry it out ?
The sealing ring swells and jams the thermostat, more often closed than open and i've had both happen
The seal at the time was impossible to get so i trimmed the old one down and the thermostat has workd perfectly since
 
Prrrgo said:
Thanks Demannu.
Perhaps I should have mentioned it, although I did in the Header to my query that it’s a 407 not a 406, but that doesn’t matter, I guess the coolant system is quite similar if not the same. It’s the ES9J 3.0 V6 petrol engine. I’m right now refitting the new thermostat and seals and will then do the factory coolant bleed and see how it goes.
Demannu, I’ve had a few of these, and never seen one run at 70C on the highway.
90C once the engine is warm always.
It will be a little while before I report on progress as the AC compressor is also being replaced and I’m still chasing one.
Any clues there for sourcing a replacement? It’s the clutch/coil that’s gone. Pump internals all ok and it was full of gas so no leaks. I’m in Ballarat Victoria
Click to expand...
You might get an electric motor rewinder to strip the coil and rewind it. seems easier than motor stators to rewind.
I have a Merc Sprinter and the AC clutch coil failed and they wanted to sell me a new compressor. But I managed to find a part number for the coil from the importer and ordered it through the local auto electrical parts supplier even though they had no separate parts reference to it. Possibly even a used one from a wrecker.
Jaahn
 
My V6 in a Monaco behaves exactly like yours. I replaced the thermostat a fews years ago after it failed shut. It takes a while to get up to temperature and sits on 70 C for a long time. If I tow it gets up quicker and sits on 90 C. My auto Xantias seemed to reach 90 C much quicker but who cares the Monaco runs fine at 70 C.
 
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