Jump to content
Click here if you are having website access problems ×

Pressurised cooling system


Rich Goddard

Recommended Posts

I know there’s loads on this in BC…over the last 8 weeks reckon I’ve read all of it.  Truly an outstanding ‘encyclopaedia' of 1000's of years of combined experience!!!   But, I’m still fishing for an explanation and DIY solution before committing £££££ for a fix.

After periods of fairly spirited driving I’m getting very high pressure in my coolant system.  After a trackday at Croft noticed the expansion tank almost full, although none of the coolant had been forced out (yet)….there was a small air pocket.

Immediately after any driving the silicone hoses are rock-hard, and even after letting it cool for 3 hours or so the pressure when I ease the cap off is very high, forcing the coolant out…fast. Surely that’s not right.

I’m well aware of the HGF issues with K-series (and in this case potential fire-ring damage causing a one-way path for compressed combustion gas) but wondering if they’re any other causes I can investigate for air being drawn/forced into the cooling system before I have it checked-in for stripping down.    (Although I’m ‘ok’ as a car DIY-er, changing a HG is probably just beyond my knowledge/facilities….think it’s removing the cambelt/pulleys etc and reassembling all that accurately that's shaking my confidence).

Thing is, I’m not experiencing any other symptoms.  No white smoke on start-up, no emulsified oil anywhere.  No apparent drop in performance.  No external leaks anywhere. No overheating….stays around 80-85DegC constantly…that seems odd to me if there’s air getting in the system.  Exception to that was immediately after a session at Croft on a hot day when the water temp peaked around 100DegC as I pulled into pits….that was first time I noticed the full bottle.

My 7 has:

  • 1.6 K-series
  • QED top-hose stat housing with 82DegC stat (OEM stat ‘guts’ removed);
  • LF cooling mod (Sept '12);
  • QED bypass connects into the submarine stub (made redundant after the LF mod);
  • Heater.

I’ve tried the obvious and cheap solution, tried 2 new best-quality expansion bottle caps. No change.

Cleaned out the gunged-up jiggle valve on the plastic plenum in case that was stopping air escaping from the head, or an open path for air being forced back into the head from the pressurised tank.  No change.

Pretty confident I’ve a filling technique which avoids air locks.  Have bleed T’s in the top heater hose and at the QED stat bypass T-piece.  Also bleed screw at the top of the vertical tank on the Radtec radiator.  Heater gets hot, top hoses and rad top get hot.

I’ve tested for combustion gas in the system at the bleed T’s at the heater and the QED stat connection….all negative so far (although going to try different method).

Any advice very gratefully received……

 

coolinglayoutpic.jpg.1968dc74c53d9968c4f3238063830f5f.jpg

coolinglayoutpic.jpg.a82bb3c53eecceb6ce1bd0c6e91cff73.jpg

Link to comment
Share on other sites

The cooling system operates under greater than ambient pressure so it's unlikely that air or gases will enter the system other than from a source with even greater pressure, this is pretty much always past the fire ring of the head gasket. Overheating can have many causes, but lasting pressurisation means the volume of the cooling system has increased, almost certainly from early leaching across the fire rings. 

Oily

Link to comment
Share on other sites

Although I’m ‘ok’ as a car DIY-er, changing a HG is probably just beyond my knowledge/facilities….think it’s removing the cambelt/pulleys etc and reassembling all that accurately that's shaking my confidence

Unfortunately on a K Series that's not really true. The head gaskets usually fail for one of a number of reasons, and it's important that the work is done by someone who knows what they are doing with a K so that they can identify, and hopefully rectify, the root cause of the failure. If you just replace the gasket, you'll be back here before very long. Get it looked at by someone experienced in Ks if you're not yourself.

Link to comment
Share on other sites

  • 4 weeks later...

So all fixed and back on the road again.

Turns out it already had a head saver shim plate and original/older style MLS gasket fitted, and looks a lot like the combustion gases were leaching between the saver shim and the MLS gasket. The hot gas had blistered the coating on the underside of the shim and the top of the gasket leading to a waterway at cylinder 1. I'm hoping I caught it early enough. Head looked (and tested, by specialist) fine after cleaning up.

I don't know what year the shim/MLS improvements were introduced, and whether they were added to the later new K engines (mine is 2004).  Either that or the original elastomer gasket had previously failed/replaced. 

Link to comment
Share on other sites

The manufacturer fix is MLS gasket plus 10 new high tensile through bolts plus uprated lower oil rail which sits below the crank. Kit can be found at www.dmgrs.co.uk. I have no connection with them but do have connections with the former Rover engineers

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...