Cooling/heater/steam problems :)

robbie123 · Post by **robbie123** » Sun Apr 29, 2007 2:28 am

Hello everyone,

Just went and collected my new car. A 1996 406 executive with the 1.9TD engine. It's in pretty good nick and has new brakes and rear suspension ect. Really impressed with the quality of the ride and handling is great. Engine is ok in 4th and 5th but sluggish in lower gears. Fuel consumption is why I bought it though! I just did 300 miles on half a tank of diesel!

Anyway here are the problems...firstly the heater wasn't working. If I press auto, the climate control does nothing so I whacked the temp up to 30C and turn it to full manually and it is blowing cold, occassionally going luke warm. Mmmmhh...I first thought maybe a knackered heater matrix but after a few other problems, I reckon I have a air lock/faulty thermostat.

The next problem was the coolant low warning light kept coming on every now and started to get a bit more frequent. At the same time I was sat watching my engine temp rise from a steady 80C to a steady 90C. After about 30mins it rose again to 100C and stayed there not movign for the next 120miles of driving. Just before I got home, when I stopped at a well lit junction I could see steam coming from the bonnet in the area of the expansion tank. Mmhhhhh....

What do you guy's reckon? The car doesn't seem to have used any oil (have one of those oil gauges that tells me on start up) so I dont think it's head gasket (hoping more like ;) ). Was thinking maybe there is an airlock and maybe the thermostat is stuck open too?

Does that sound plausable? The previous owner was honest with me and said that he thought the thermostat was playing up and he had changed the radiator not that long ago due to a leak.

So tomorrow I am driving 80 miles back home(at uni at the moment) to give the car a good clean and a quick oil change. Before I go I was going to top up the coolant just to get me home and then tomorrow afternoon give the cooling system a good flush through and then fit new thermostat and give the system a good top up.

My only questions are...where is the thermostat and is it easy to change?

What are the bleeding points on the car?

If I give the system a flush and a coolant refil, any tips on the best way to do this and any particular way to top up?

Cheers guys,

Have done a bit of reading on here but my Haynes hasn't arrived yet so as much advice given is greatly appreciated!

P.S: I'm not a car forum newb! My previous car love was Volvo 480's and I was a memeber of the owners club/forum. Used to do all my own repairs but needed diesel economy so had to go for a 406 and I haven't a clue about diesel engines!!!

PPS: Oh and my aircon works REALLY well!!! Happy days

mbell666 · Post by **mbell666** » Sun Apr 29, 2007 5:07 pm

Hi

It may just not have been bleed corectly.

The heater matrix is the highest point on the system (higher than the water tank) so if no bleed correctly it will air lock. There's a bleed value where the pipe join on to the heater matrix. The haynes manuals normally recommend making header tank for the header tank when filling them.

Thermostate normally jam open when they fail, making the engine take longer to warm up and the temp to drop when going down long hills etc. So probably just the air lock in the system.

On the HDI the thermosate is really easy (3 * bolts), its on the front of the engine at the top right on the main feed for the radiator. Wouldn't expect the older DT's to be much different. They aren't expensive so if you need to bleed and top up the system you may aswell change it for peice of mind.

The temp should sit around at a constant 85 to 90 once the egine had warmed up.

philg · Post by **philg** » Sun Apr 29, 2007 6:12 pm

as said above. the previous owner says he changed the radiator, so a likely cause of your heating woes could very well be air in the system. Bleeding the air can be a lengthly process as whenever you think you have all the air out, there will more than likely be more. Just keep going through the bleeding process over and over. The haynes manual will keep you right, just make sure you use a heater tank of sorts, like they recommend in the haynes.

I dont know if 406's are the same as 306's, but hte 306 radiator had 2 fans, one would come on once the engine reached 90degrees, and both would come on if the engine hit 110degrees. I've had 2 306 dturbos, and they both constantly ran at about 75-80degrees, They would only hit 90 when sitting still at traffic jams. they NEVER went over 90degrees. I also ran my 306's on pure anti-freeze/coolant, with no deionised water added, i always believed this was best for them.

ps. dont just trust that oil gauge for the head gasket. open the oil cap, and check the dipstick for the mayo type substance thats a sign your gasket is busted.

robbie123 · Post by **robbie123** » Sun Apr 29, 2007 6:21 pm

Well...Topped up collant this morning and started the engine (after a bit of trying - damn you glow plugs!!!!!!) and the car deposited alot of it's coolant over the floor(Radiator by the looks of things!). Coolent low light was on constantly!!! Tried to drive and after about 5 mins of dual carriageway I watched the temp shoot from 70C to 110C in about 10 seconds(not any more than 110C though!). Immediately floored the clutch and coasted off the junction watching my engine temp drop because of the fan kicking in (I guess). Pulled up and off with the engine. The car quite rapidly emptied even more coolant.

Rang the AA and he confirmed the radiator was shagged (the previous owner had put it on off a scrap 406 so was secondhand). Anyway to cut along story short...GRRRRR!

Went home on a truck and saved myself a tenner in fuel - wahey to the AA

So...I am going to remove the radiator and thermostat, Flush the system right through, and then fit a new thermostat and radiator(wahey for ebay - £61 and guranteed delivery by 3 on tuesday).

How should I fill the system up though? Apprently I need to fasion a header tank. Is this just a bottle chopped in half and taped in place? I'm guessing I keep putting coolant into the make shift header tank fills up. Then open the bleed valves and let it carry on as it should. I heard i should put the heater on full temp/full blow so does this mean I start my engine? If someone could maybe do a "how to" on refilling the system I would be most grateful.

Next query - the thermostat...what does it look like? Is it the grey thing with a black cylinder on it, on the front of the engine? I have looked online and seen thermostat housings for sale. Is this the same as the thermostat or another part?

Anyway hopefully by tuesday, I will have a nice, working 406...fingers crossed eh?

mbell666 · Post by **mbell666** » Sun Apr 29, 2007 8:27 pm

You can't see the thermostat until you take the thermostat housing off. Hard to describe what it looks like, just have a look when you pick one up.

To fit you unbolt the housing, pull it off, pull out the old thermostat. clean the housing and put the replacement on in. Making sure you fit it the right way round. re-fit the housing.

The thermostat housing is probably on the engine side of the top radiator hose, may have a bleed valve on it.

robbie123 · Post by **robbie123** » Tue May 01, 2007 3:13 pm

Ok...Well i fitted new thermostat, new radiator and replaced teh coolant and bled it with the bleed nipples while filling from a coke bottle header tank! Started driving and looked out the rear view mirror to see puddles! Stopped and it turned out that a previous owner has repaired the bottom radiator pipe by fitting a stainless steel pipe inbetween a break and then jubilee clipping at either side...unfortunately, I undid the jubilee clip and thought it was on there for no reason so didn't tighnen it back....SO after lots of swearing, I re-repaired the pipe, and this time I topped the car up with a weak coollent mix (20% collent rather than the suggested 33%) in case it blew again (it's a tenner for 5 litres so I don't want to wash the drive with it!!!) and went through the bleeding procedure again. Opened the heater matrix bleed valve with engine going just to check all the air was out as the heater wasn't hot and had the cap blown out of my hand!!!! Grabbed another off the front wheel and blocked the waterjet now spraying from the bleed nipple and managed to get the cap on. Noticed a little leak so tightened the pipe and then all was well. Took it for a 20 minute drive. Seems to like sitting between 90 and 95. If it goe's over 95 the fan kicks in and brings it down again.

I'm going to remove some coolent now and refil a bit of undiluted to get the coolent mixture a bit better. Then hopefully it will last! I don't know though - the system seems to get quite pressurised so I may still have a bit of air left in the system but I will try and get it out later. I'm doign a 80 mile trip tonigth so we will see if it lasts - If it doesnt then I reckon it is getting too pressurised and might be the headgasket. No oil in water/water in oil though so i'm not sure.

Cheers for the advice though!

robbie123 · Post by **robbie123** » Tue May 01, 2007 4:59 pm

Well it's building too much pressure. Got a small puddle just while idling from steam coming out of the expantion tank cap(you know how it lets pressure out) so it looks like I have a headgasket gone! Really annoyed - the guy I bought it off must of seen me coming eh? He must of just topped it up with coolent and the radiator we took out looks like he patched it so i'm guessing it was all done to disguise the problems.

Oh well life goes on eh? I am now trying to get a decent "mates rate" quote for the headgasket but i'm running short on contacts who have the time off to do this job. I will probably try and do it myself. Are they easy to do on these engines? I guess just remove everything in the way, take the head off, get it tested and skimmed and then refit? Is haynes any good on this good? I have mine in the post so hopefully it will be clear!

jameslxdt · Post by **jameslxdt** » Tue May 01, 2007 7:53 pm

depends how and why its gone, unfortunatley on the 1.9 dt it works out cheaper to put another engine in as when the gasket goes it usually takes the piston rings with it, but more often than not, the con rods, so it wont run properly once the gasket is done, if you want rid of it, ill gladly have it

its a fairly easy gasket to change, the main issue is that the engine is at a 60 degree incline to the bulkhead, so as you can guess getting the head out is a bit of a bitch

robbie123 · Post by **robbie123** » Tue May 01, 2007 8:16 pm

Well a friend of the family is going to look at it and take the head off. If it is cracked or any internal damage I will get a new head from a scrappy. I'm really hoping it can be sorted cheaply! At least it means when the engine is in bits, I can change the glow plugs easily

Fingers crossed he can sort it as he won't charge much at all.

Peugeot Keith · Post by **Peugeot Keith** » Wed May 02, 2007 8:26 am

Robbie, Sounds like your problem is similar to mine see my thread " 406 HDI coolant air lock".
Before you start taking the thing apart just try running it without the stat and see what happens. Mine has stopped chucking out water and pressurising since I did this. Now I have to get the stat back in without the air and I'm convinced it will be OK

Post by **Welly** » Wed May 02, 2007 8:59 am

jameslxdt wrote:when the gasket goes it usually takes the piston rings with it, but more often than not, the con rods

Are the Pistons *very* close to the HG on the XUD engines?

Is this problem above not the Water Pump?

niz406 · Post by **niz406** » Wed May 02, 2007 11:39 am

Its the TD you say... have you changed your water pump? It could also be a damaged turbo.... if the waterways are cracked in tghe bearing core... it is the same as a gasket failure... where coolant pressure is crazy....

Remove your glow plugs and put a bit of paper towel into the cylinder to see if it mops up any water / coolant! If it does it's HG if not.... its something else...

Post by **Welly** » Wed May 02, 2007 1:11 pm

Nizzy you silly sausage have you seen the thread size of a glow plug, you'd struggle to get a cotton but down there

(Nizzy don't like Diesels)

I would put money on the fact that it is NOT the HG.

I don't know about the XUD turbo but on my HDi it has an Oil supply only, no water connections as they run a lot cooler than petrol.

Even if it was the turbo water connection then you would just loose water into the zorst rather than pressurise the cooling system IMO.

My money is on the water pump here and you may find that the pump impellors have dissapeared. No circulation = over pressurisation.

niz406 · Post by **niz406** » Wed May 02, 2007 1:26 pm

Sorry you are right.... Turbo is only oil fed....

You can get something in the plug holes to check... seriously this is the easiest method to check for water in the cylinders

I bet its the waterpump...

robbie123 · Post by **robbie123** » Wed May 02, 2007 7:44 pm

Does the water pump run off the cambelt or off the auxuillary belt? To check if it is headgasket, could I not get a CO2 detector strip thingy and put it over the open rad expansion tank?

I spoke with a friend of the family who specialises in diesels and he said the engines are rock solid until they overheat and then they normally pop their head gaskets and I reckon the previous owner has overheated it hence the suspicion! He is over 150 miles away so another freind of the family mechanic is going to take a look but I will tell him I suspect it could also be the waterpump.

Cheers for the suggestions guys. I will also check the engine with the thermostat out.

Rob