New headgasket, still overheating!!!

Allanxantia · Unread post by **Allanxantia** » 23 Jul 2006, 15:20

Spent all weekend doing headgasket, skimmed and pressure tested it and is still running too hot, and amount of hard driving and the guage flies up. I have had the radiator off and flushed it out fully, and carefully bled everything. once fan comes on it never goes off, basically same symptoms as before. My plan is now:-

Take inlet manifold off and retorque the headbolts. I have a horrible feeling I forgot to grease them so if that were the case then they would not be tight enough and may be leaking.

I got the 5 notch repair gasket from GSF and it did not have torques on the label so I used the ones in the haynes. An error I suspect, anyone any ideas what torques I should use?

AndersDK · Unread post by **AndersDK** » 23 Jul 2006, 15:54

Oh well -

But the overheating has NOTHING to do with the headgasket or headbolts torque - NOTHING at all. The headgasket failed because of the engine overheating in the first place - NOT vice-versa

You GOT to understand this - or you will get stuck in a money pit problem

Leave the head, gasket and bolts for now

Then concentrate on anything related to cool down the engine

You should always suspect your own work. Even the best of the professionals makes mistakes - or overlook the obvious.

1) Check the engine timing. Its TOO easy to get it wrong by one or 2 notches on the cogs. This will always affect the running temperature. The later XU's have e very nasty habit of disintegrating the rubber on the crank drive pulley - leaving you with a havock timing. Always use the timing hole found under the starter motor into the flywheel. Be patient : remove the starter to find the timing hole. Its a nusiance to find - but it is there.

2) Check the coolant hoses : are there any kinks on the hoses that may possibly block the coolant passage ? This is very important. Check ALL the hoses - dont spare yourself to assure this all checks ok. Imagine yourself forking out £150 on a new radiator - just to find it was a "kinky" hose

Especially the one that leaves bottom of radiator on (cars) RH side and enters the water pump housing - this hose is known to play bu***s.

3) Next suspect is the thermostat - the common one that is located in the outlet housing of the cylinder head - right where the large top hose to the radiator is connected.
The thermostat may be defective - i.e. has broken and is keeping itself shut.
Or worse yet : it may be fitted the wrong way around.
The small cylinder that operates the thermostat flap MUST point inwards to the cylinder head - not to the radiator hose.
If you have no record on the thermostat - then replace it. Its only some £6. Or try run the engine/car with no thermostat fitted.
If the engine then never seems to reach a warm temperature - what do YOU thnk then ?

4) Then the electric thermoswitch in the radiator side tank. Its a 3pole temp switch - with heavy gauge wires. This is known to burn out in the low speed (1. stage) switch - leaving the temperature to raise far enough to always cut in the Hi speed (2. stage) switch. But even running on stage 2 it should cut out at intervals - reaching an equilibrum.

Please no shortcuts - and do the above tests in the order shown please

Good luck.

simonelsey · Unread post by **simonelsey** » 23 Jul 2006, 15:58

Had a carina with same prob , thoaght head gasket , but took into garage turn out water pump stuffed and raditor blocked , no seeign as rad ok I would suggest checking water pump.

deian · Unread post by **deian** » 23 Jul 2006, 17:39

in addition to AnderDK's reply.... Does the radiator get hot? if not then the suspect could be the thermostat.... if it does get hot then you need to check the fan switches, but AnderDK know what he is talking about so follow his points first. It will be one of them for sure.

slim123 · Unread post by **slim123** » 23 Jul 2006, 21:10

Just a quick note.

You shouldnt grease head bolts, as if you do the grease can form a hydraulic lock in the hole, this way even though the torques read the same, they wont be!!

A light oiling is all that sould be done.

Regards
Slim

slim123 · Unread post by **slim123** » 23 Jul 2006, 23:07

Just a thought, does the car have aircon? If yes then clean through the condensor (rad in front of the rad!) There is allways a build up of muck and stuff between the two and this can cause an overheat.

I guess that the rad is getting hot, otherwise the rad sensor would not get hot and not set the fan off.

You say that you have flushed the rad through, but bear in mind that the rad is made up of several thin flat pipes to transfer the water from one side to the other, if only a few of these are clear you will get a good flow from one side to the other with a hose pipe, but not through the cars cooling system.

When the car is warm switch off and check for cold spots in the rad, it should be the same temperature all over, if cold spots are found this will tell you that the rad is partly blocked.

Regards
Slim

Unread post by **Peter.N.** » 23 Jul 2006, 23:34

If its done 100k miles or more it probably needs a new radiator.

Allanxantia · Unread post by **Allanxantia** » 24 Jul 2006, 01:00

Well, I've now tried it with the thermostat out and it makes a massive difference, however the temp guage still rises very quickly when I give it amy length of on-boost driving.

There appears to be problems with the fans, no low speed and high speed only on the O/S fan, also condenser rad looks really blocked.

I am just going to remove it as A/C doesn't work and I have no intention of fixing it!

The trouble with all this is that I can't really remember how the guage behaved before I had all these problems.

I will rectify all these before I worry about the head again

Allanxantia · Unread post by **Allanxantia** » 24 Jul 2006, 01:01

Well, I've now tried it with the thermostat out and it makes a massive difference, however the temp guage still rises very quickly when I give it amy length of on-boost driving.

There appears to be problems with the fans, no low speed and high speed only on the O/S fan, also condenser rad looks really blocked.

I am just going to remove it as A/C doesn't work and I have no intention of fixing it!

The trouble with all this is that I can't really remember how the guage behaved before I had all these problems.

I will rectify all these before I worry about the head again

Unread post by **RichardW** » 24 Jul 2006, 07:36

Whilst the fans may not be working correctly, this is not your problem. Once you are over 30mph the fans do nothing to keep the engine cool. If it suddenly started this behaviour, then it is also unlikely to be crap in the radiator sandwich. I think 2 possibilities are left: the rad is blocked, or the water pump is goosed. Since it came on quickly, I think this points to a sudden failure, rather than an accumulated failure - and my money therefore is on the water pump. There's always the possibility that the bottom hose has gnoe baggy, and is collapsing under high suction, but that sounds like another gradual fault.

mezuk04 · Unread post by **mezuk04** » 24 Jul 2006, 08:46

Peter.N. wrote:If its done 100k miles or more it probably needs a new radiator.

I would second that.
Ok so its not cheap for a brand new radiator but then the thought of a head gasket problem would serve the car possibly useless for me personally. When I got the Xantia it was reading about 85 constant but the radiator had a tiny leak (or we thought it did at least) so managed to get the price of a new one knocked off the sale. Fitted new one and the temperature always stayed at about 65 (from memory).

jeremy · Unread post by **jeremy** » 24 Jul 2006, 08:55

Richard - how can the water pump cause overheating - unless you mean the the impeller falls off or corrodes away - both of which are unlikely.

Its other problems are likely to be bearings (makes a noise) or leaks - to the outside world - but neither of these is likely to cause overheating.

Unread post by **Peter.N.** » 24 Jul 2006, 09:48

In 50 years of motoring I have only ever had two causes of overheating and they have been either the thermostat or the radiator, if you have changed the thermostat that only leaves one! On my last CX diesel I had to change the radiator 3 times, it had covered 114 k when I bought it the 'digital temeperatur gauge almost invairiably read 85C, it then went up to 86C and shortly after to dangerously hot, I changed the rad, back to 85C, about 100k miles later 86C - new rad - OK and again at + another 100k. And I would agree with Richard, the cooling is little affected by the fans a once you are moving at a reasonable speed.

I fitted a new head gasket tp my XM last year and replaced the radiator for good measure. I dont want to have to do that job again.!

Unread post by **RichardW** » 24 Jul 2006, 10:04

"Richard - how can the water pump cause overheating - unless you mean the the impeller falls off or corrodes away - both of which are unlikely. "

Correct. See this post from a while back, where a ZX was oveheating, HG replaced, still overheating. New water pump cured it.

Overheating ZX

I can't see that a radiator being blocked would cause a sudden move to overheating. Got to be something mechanical or hose related. I think since the Xantia uses a 2 pass radiator, the velocity must be pretty high which should help reduce fouling - you hardly ever hear of Xantia TDs needing new rads because they're blocked (but then perhaps that's just because they're made of chocolate and get replaced before they get to that stage!).

Allanxantia · Unread post by **Allanxantia** » 24 Jul 2006, 10:09

With the thermostat out, what temperature should the engine be running at in normal driving? bearing in mind the heatwave just now! If I am driving normally and gently it sits at 80 but with some hard driving it goes up to just over 90. From the temperatures stated in the BOL the thermostat isn't even supposed to be fully open until 99, so maybe this is normal?