Head gasket??

[Dannyboy]

Chaps, a problem is occuring and I would like some guidance as to the possible roots of the this!

 

In essense..

 

I have replaced the thermostat, refilled the water system, bled the system.

 

On driving the car, temperature stays fairly normal, however when idling it has boiled and does rise to 90 degrees plus, to alleviate this i turn on the heater and run this on hot, this bring the temperature down again.

 

When the car boiled the other day, the fan did not kick in, however it does normally!

 

 

There is no emulsion on the oil filler cap, no obvious oil in the water, however, when I turn off the engine after a run, the water system appears to have been pressurised and the header tank weeps water. Letting the engine cool and removing the cap from the header tank the water system remains pressurised.

 

Thoughts??

 

cheesy geezer 😬

[Dannyboy]

No one any ideas??? 🙆🏻

 

cheesy geezer 😬

[Harry Flatters]

Dan, still sounds like an air lock to me. When you bleed the system, make sure the heater is open and jack the front of the car up as high as you can. This should ensure no air locks. You may need to repeat the process a couple of times.

 

Good luck - see you this evening I hope.

 

*arrowright*Harry Flatters *arrowright*

AKA Steve Mell of Su77on Se7ens and Joint AO - Surrey

[Dannyboy]

Thanks Steve,

 

Will attempt to bleed the system AGAIN!!! poxy thing!!! covering myself in sticky hot anti-freeze!

 

Still confused regarding the smoke emission from the exhaust at tickover!!! Over-fuelling??

 

cheesy geezer 😬

[Harry Flatters]

What colour smoke? I doubt overfuelling would cause smoke, would be smelly though. With all this beeding etc at tickover, it may be that you are a bit oiled up and need a damn good blat to clear things out. On the other hand if you are burning some oil and the water system pressurisation problem persists then your original head gasket theory may hold water or not

 

*arrowright*Harry Flatters *arrowright*

AKA Steve Mell of Su77on Se7ens and Joint AO - Surrey

[scooby dooby doo]

if it boiled over then the header tank cap is probably scrap - replace it.

 

HOOPY

R706KGU Hoopylight R

[SLR No.77]

Mine's boiled over a few times whilst trying to sort the air-lock problem, cap seems fine, so maybe don't worry about that one yet.

I had two problem areas for air-locks:

1. heater - very difficult to bleed the system due to the nature of the heater piping. After filling the rad through the top hole, jack up the front of the car and fill by disconnecting the top heater hose - both into the heater and the hose. The heater valve obviously needs to be open. When full at both sides, re-make the connection. But before that ......

2. The layout of the piping around the thermostat can lead to trouble. From new on my car (and on most of the other Ks i've looked at) the small "j" hose from the stat is positioned to be below the large bottom rad hose. This causes the large hose to be "uphill" at the 180 deg bend from the stat. Air goes up, water goes down. If you reposition (re-plumb?)the hoses so that the rad hose passes below the J hose, air will run nicely out of the hoses as soon as the stat opens. It was only after I made this change that my "bleeding" problems went away

 

Exhausts are sometimes a little smokey when absolutely cold anyway - you don't normally see it on most cars - as Harry says it could just need a good blast.

 

Stu.

[c21vhpd]

I have found, all be it on a 21 with a horizontal radiator instead of the vertical one on a 7, that a successful bleeding technique is thus:

 

1) Disconnect the radiator inlet hose from the water rail.

2) Fill the cooling system from both the header tank and the radiator inlet tube. You won't get the hose completely full, but you should get all air out of the radiator.

3) Reconnect the radiator inlet hose.

4) Make sure that the heater slider is open.

5) Disconnect the hose that goes from the other end of the water-rail to the heater.

6) Cover both the exposed ends with your thumbs.

7) Blow into the header tank, unsealing first one thumb until coolant squirts out, then the other.

8) reconnect the heater hose.

9) top up the header tank.

10) run the engine up to temperature with the header tank cap off, to aid air escaping.

11) tighten the cap and run for a couple more minutes to check that the temperature is stable.

 

This only failed once (and lordy knows I've done it enough times!), and it's because I forgot to keep the cap loose when running up to temperature.

 

It works for me - if it works for someone else too I'll be delighted

 

Honda Passion Orange, 640kg , and proud of it

[Steve Kirk]

 

Actually 90 degrees plus or even a bit more is not necessarily terminal as long as it doesn't keep climbing, esp as to some extent the gauges do vary. Does the temp keep climbing?

 

When you say it has boiled, what do you mean - that it has reached 100, or that the water has actually overflown? If the latter, try replacing the pressure cap if fitted (not sure what car you have). If the former that would make me nervous too, maybe check that the engine isn't actually running hot (e.g. on XFs this can be too much ignition advance or weak mixture).

 

I had a XF car a few years back that suffered from this same problem when stationary. I remember being told at the time that XF engines (esp modified ones) like to be a fraction "nose up" in the car, and they can sometimes be prone to overheating if they are pointing even slightly nose down, because apparently water can get trapped at the back of the head creating a hotspot, creating a steam/air pocket, and hence the symptoms you describe. This can happen if the car is paked on an uphill slope post-blat.

 

Also take off the nose cone and check that there are absolutely no signs of leaks all round the rad - including sides and bottom - and the hoses and sender fitments. If it's leaking, bin it, esp if it's an old type rad. Rads are cheaper than engines - I know this from recent experience ☹️