Pressurising Coolant System - confuddling!

[philg]

Having a bit of a problem here with the 1.9td,

Coolant system is pressurising and hissing out the overflow pipe BUT ONLY if the car is driven hard, the radiator-thermostat pipe becomes rock hard with the pressure.

The headgasket was recently changed, and a head that was pressure tested and skimmed approx 1000miles ago fitted.
I used New stretch bolts, but just a regular gasket as the motorfactors didnt have a steel-multilayer jobbie in stock.


The Car IS NOT mixing coolant/oil
She is NOT burning the coolant or oil
She is not overheating, sits at about 77 degrees, and will fit 90 in a traffic jam before the fans kick in.


I swapped the coolant cap with my bro's 1.9td and it made a little difference but not much.
Radiator is also about 5000mile old.


So what the hell is going on?! I'm confuddled, and REALLY dont wana take the head off this thing AGAIN!!!

Please help

[jasper5]

Have you changed the thermostat? Did you bleed the system properly?

If these things have been done properly, I can only think that it might be the head gasket.

These engines are very sensitive to having the correct head gasket fitted, fit the genuine Peugeot head gasket.

I have had problems in the past because of this.

You will need your chassis number.

[philg]

Havn't changed the thermostat you know, but didnt think it was at fault due to not overheating or always runngin cold etc. May well try it tomorrow for piece of mind.

Changed the coolant umpteen times to no avail, and correctly bled everytime. Currently running 90%coolant 10%water.

I really shoulda fitted a steel multi-layered gasket! chassis number wont matter a shite, think this is the third engine ive had in this car lol, she's running a D8A engine from a '95 306 dturbo at the minute.

(1st engine dropped a pre-combustion chamber into the piston, 2nd engine blew piston rings..... probly shouldnt have been running 24psi of boost on a high mileage engine lol)

[TehAgent]

These cars run hot, think the temp the fans kick in is around 96 to 97 degrees before the fans kick in, sounds like you have a dodgy sensor to me. and correct me if im wrong, but shouldn't it be a 50/50 mix of water and coolant?

[philg]

These cars run hot, think the temp the fans kick in is around 96 to 97 degrees before the fans kick in, sounds like you have a dodgy sensor to me. and correct me if im wrong, but shouldn't it be a 50/50 mix of water and coolant?

ive had 4 306 1.9td's and in all the first fan kicks in at approx 90 degrees, and ive never seen the second fan kick in as she's never went over this 90, but its suppose to kick in at 110 i believe.

Yes it should be 50/50, but i tend to flog these things and have the boost and fueling both turned up quite a bit so i prefer to run more coolant. However i was running approx 50/50 and it was no different.


edit: maybe your on about your petrol, yea i think the fans kick in higher on them, i had a 406coupe that i used to worry about the temp as i wasnt used to having a petrol lol

[jasper5]

There are several thickness of gasket fitted to the 1.9 engine, the correct gasket having cut-outs on the edge of the gasket the same as the original, if you don't believe that you won't need your chassis number to get the correct one, the best advice is to fit the thickest one available.

I always fit a new thermostat when doing a head gasket job.

[mjb]

ive had 4 306 1.9td's and in all the first fan kicks in at approx 90 degrees, and ive never seen the second fan kick in as she's never went over this 90, but its suppose to kick in at 110 i believe.

406s don't control the fans independently. At around 90c both fans run in series (half speed), then about 100c they're run in parallel at full speed. The ac temperature can override this behaviour though

[philg]

ive had 4 306 1.9td's and in all the first fan kicks in at approx 90 degrees, and ive never seen the second fan kick in as she's never went over this 90, but its suppose to kick in at 110 i believe.

406s don't control the fans independently. At around 90c both fans run in series (half speed), then about 100c they're run in parallel at full speed. The ac temperature can override this behaviour though

Apologies, this is a 306 im on about, and the fans do come on 1 at 90 the other at 110. Similar engine as the xud9tf hence im asking here.

@ Jasper, it is the thickest gasket on her at the moment due to the head being skimmed. Cant remember if it was 5 or 6 notch on the gasket itself, but its definately the thickest.

[jasper5]

Ok, no problem, just had aggro a long time ago with one of these, genuine head gasket fixed it.....a lad I knew at the dealers pointed me right when I was getting frustrated with a job using a Payen gasket.

Usually, the only reasons for pressure in the system are stat problems, pressure cap, or head gasket problems.....any chance of doing a "sniffer test" to check for exhaust gasses in the water?

Of course, you could have a blocked radiator...........check for cold spots with the stat open.

[Welly]

I understood that the more 'coolant' you have the worse the heat-transfer is!

Water is THE best medium for transfering heat but it lets the block go rusty so you need the anti-freeze to help with this and other things but not too much of it. It is primarily for winter protection not 'cooling' as such.

I've heard of people running turbo'd Jap cars with 'Water Wetter' in the system and seeing a temp drop of 3 to 5 deg C

[philg]

tits mc gee, had her out a 'spirited' drive earlier today, and just after i stopped steam and water were spraying out the overflow pipe

so took out the thermostat and threw it in 90degree water.... and watch it open

The cars for the Mot on monday morn, so whether she passes or not by monday night i plan to have the head off her. I feckin hate headgaskets!!!

Will be sending the head away for another pressure test, just to be sure. Does anyone know do the engineering places prefer for the head to be stripped for a test, or is it supposed to be complete?


@welly, turns out your correct, i did some reading, for some reason i always thought coolant did the cooling lol. Water will be in the majority next time i fill.

[jasper5]

I usually take the head assembled, but without manifolds, to my engineering place.

I would fit a genuine head gasket next time and make sure you follow the correct tightening data.

Fit a new stat as well, making sure the system is bled properly.