Coolant in oil after head gasket blown.. Any thoughts on main cause?

[Mogmike]

Hi .. I have the dreaded head gasket blown at 56k miles on my 2004 Rover 75 1.8 petrol engine. I'm about to take the head off and check the liner height as recommended on the site here before buying the full kit to change everything. My question is that all the coolant has gone into the engine and formed a thick coffee solution in the sump. The rad and water hoses are empty. Doe this point to any particular part failing..? Other than the head gasket itself.. Obviously I will be changing the water pump, thermostat plus the cambelt and shall check the head and inlet manifold for any distortion.
I would welcome any thoughts and comments.. Many thanks... Mike

[Yorkshire GOC]

Hard to tell - the HG may fail when stressed by heat - so did you have a temperature event(s) or losing coolant prior to the "mayo" forming - if so could be leaking coolant hose, a classic failure point being the plastic t -piece behind top left on the RAD or failed water pump.

If no temperature event then some posit that Orange OAT coolant has a weakening effect on the gasket - research the posts on here and draw your own conclusions - I have looked at the debate and as a consequence use non OAT blue coolant in may car for the last 4 years.

[Rich in Vancouver]

I feel your pain!
In my case it was one of the HG silicone tracks that went.
Liner heights were OK so I used one of the SAIC gaskets and
it is still going strong several years later.

[T-Cut]

Exactly like Rich in Vancouver, I had the classic original elastomer failure. There had been small coolant losses for a few weeks but there was never an overheating event. It just happened. A lot of the coolant was dumped into the sump. I wasn't many miles from home and managed to limp it back. The coolant/oil mixture formed a viscous black liquid resembling tar.




Was it the 50% OAT that finally broke the elastomer adhesion? I dunno. I replaced it with the Payen elastomer type. No way would I consider the MLS solution.

EDIT: 2004 1.8 Turbo 34,000 miles

TC

[suzublu]

Originally Posted by T-Cut

Exactly like Rich in Vancouver, I had the classic original elastomer failure. There had been small coolant losses for a few weeks but there was never an overheating event. It just happened. A lot of the coolant was dumped into the sump. I wasn't many miles from home and managed to limp it back. The coolant/oil mixture formed a viscous black liquid resembling tar.




Was it the 50% OAT that finally broke the elastomer adhesion? I dunno. I replaced it with the Payen elastomer type. No way would I consider the MLS solution.

EDIT: 2004 1.8 Turbo




TC

Exactly the same as mine

[T-Cut]

From my experience and reports from others, if OAT is truly the cause, then these gaskets were never fit for purpose. I think I'll do a compatibility test on the OEM elastomer to see whether 50% OAT does actually affect it over time.



TC

[Yorkshire GOC]

Is it not the case the reason OAT was specified was that it requires only a 5 yearly change as opposed to say blucol which is 2 yearly and was primarily done to get the company car market.

[T-Cut]

Originally Posted by Yorkshire GOC

Is it not the case the reason OAT was specified was - - - - -

Probably. But did MGR assume their particular gasket was resistant without testing it? My head had pink-coloured staining around the failed beads, but nowhere else.



The prevalence of HGF in the K16 suggests that adhesion failure of the elastomer beads is the underlying cause. MGR introduced the PRT system to the K16 specifically to mitigate against thermal gradients that were said to be the crux of the problem. Yet the PRT engines continued to have HGF. As illustrated above, many failed gaskets have fully functional fire rings. Nowadays, OAT type antifreeze is the most commonly specified and today's elastomer gaskets are tolerant.

TC

[Mogmike]

Firstly.. thanks to TC, Yorkshire GOC, Suzublu and Rich in Vancouver for getting back and giving your comments.. Secondly apologies for my late response but I've been pontificating..and delaying the inevitable strip down. It looks like the consensus of the likely cause and failure point is elastomer failure of the head gasket..
I've just started today having boned up on as much info as I can. There seems to be comment in K engine write ups about the inlet manifold which if failing to seal will put water into the pots.. So I'm starting to look there.. I have found some coolant in the main tube from the air filter to the inlet manifold .. Not sure what that means but the filter is as clean as a whistle.. Maybe just vapour turning to water from when the white smoke/steam came out of the exhaust. Also when draining (and carrying out initial cleaning flush..the coolant wasn't contaminated by the oil.. at least only superficially but no espresso coffee..)
I will post updates of what I find as I go now but just for info I did get an overheat light on first, and topped up with water twice to get home. After the first refill I did about 15 miles before it started missing and the light coming on again. It took a lot of water on both refills. I also note that it has the thermostat on the outlet side ( now located in the hoses on the near side behind the radiator) so must be a mod on the 2004 model I have.
I could kick myself for not checking levels regularly knowing the bad history that follows this engine. Probably checked 1000 miles ago. Incidentally my car has only done 56K and has a very thorough service history.. even the oil was clean when I bought it back in January.
Inlet retaining nuts are all off and started taking off the plumbing but rain stopped play..( yes I'm having to do it outside on the drive..😕.) But have a garage where I can work on the bits I take off.
Can't wait to get to the head gasket and see what I find. 👀.. Thank you all again

[SD1too]

Originally Posted by Mogmike

I also note that it has the thermostat on the outlet side ( now located in the hoses on the near side behind the radiator) so must be a mod on the 2004 model I have.

Do you mean something like this Mike?



This is the aforementioned PRT: Pressure Relief Thermostat.

Simon