Head gasket blown after extended hot running- should I be worried?
Turbo Mini Forums

Hi guys. just after a bit of advice on this one:

i've just got back from a trip to the nurburgring with TMF, during which mini had a few temperature issues.

Cruising tot he ring from dunkirk, the water temperature ran at about 95-100 degrees, which I didn't see as a huge problem really.

Around the ring, along the back section of the track where it climbs up hill, the car reached a peak of 111 degrees C, and felt like it lost power. we backed off and the temp dropped to 95, and all the power came back- happy days. end of the issue I thought.

On the way home from the ring, we were driving in 29 degree abmients, and despite having a mech fan, a kenlowe sucking on the back of my minispares 4 core rad, and the heating blowing on full, I couldn't get it to run at less than 100 degrees for the entire 6 hour drive to the ferry, although it didn't at any point go above 102.

The engine runs in a fairly high state of tune, with a CR of 11.8:1, and an MED full race 37x30 head.

On the first use of the car back in england after the trip, the bk450 HG popped between 2 and 3.

I pulled the head last night, and was shocked at what I saw.

the inside cylinders are running leaner than the outers, which i expected anyway, but the freshly skimmed surfaces on both my block and head have blackened,and the gasket looks scorched with what looks like some serious heat build up having occured between all cylinders.

Also, the pic doesn't show it well, but no2 piston is covered in tiny dimples, are these an early sign of DET?

it was set up on the rollers earler in the year holding 11.5:1 AFR's across the whole range.







Should I be worried? or is that kind of discolouration normal after 2000 miles use? last time the head was off in January the discolouration was nowhere near as bad, but it hadn't been subjected to such sustained use before.

Sorry for the mega long post!

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

I bet thats one of the dodgy batch BK450s. It looks to me that all the fire rings have been blowing.

Paul

I seriously doubt it!

hmmmmm, I hadn't thought of that Paul, that gasket went on in january, so I thought that was before the manufacturing cock up.

it does definately look like all the fire rings have been blowing through. I havn't felt the car's been running 100% for some time now, especially top end feeling a little lacking.

Also, I don't know if it's related, but in the week leading up to the gasket failure (I think it started on the ring) it developed a top end misfire above 6500 rpm. that could of course be totally unrelated.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

As above, there appears to be fire ring leakage everywhere.
Oh i wonder if those tiny dimples were caused by that missing chunk of gasket. Has the chamber got any marks?

Edited by T3Tone on 16th Sep, 2009.

-MINI CLUBMAN 1380 TURBO-

Agreed, it has been blowing between 1-2 and 3-4 as well, just didn't reach total failure as it's slightly stronger at the other two points.

The black is just the carbon from the blowby.

I would do a very careful straight edge check front to back at those three points both block and head (once the carbon is cleaned off)

Just because they have both been skimmed, doesn't mean they are flat now.....

Schrödinger's cat - so which one am I ???

You may benefit from changing to a 2 core rad as well.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Happy birthday Prawn. Hope you're enjoying your present from payen. lol

haha, cheers AP what a lovely birthday present it is too!

I switched from the super 2 core rad to the big 4 core rad a few years back after having heating issues on the old 2 core, but i now think this was caused by something else.

my old man is bringing up my super 2 core rad this evening and I'll whack it on and see if things run colder. I'm also changing from an 82* stat down to a 74*, drilled with 6 6mm holes around the rim to act as a bypass and improve flow.

I'm a little shocked at the amount of carbon build up really after just 2000 miles. When it went together it was all shiney clean metal, and it's only ever been run on v power, which is supposed to keep things clean and great. Clearly it doesn't do exactly what it should.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Across all 3! Thats a little odd get your torque wrench checked as well.

Own the day

Changing the thermostat for a different temperature wont make a blind bit of difference when the engine is running at 100c.

Turbo Dave used to have serious cooling issues that he could not resolve until he changed to a different block, then the problems went away.

Personaly the drilled holes in the thermostat, while are A solution, they are not THE solution.

I would do as Mr Joshua suggests and check your torgue wrench.

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

well. funny you should mention torque, as I had a bit of uncertainty about it when i did torque it down.

i fitted ARP studs, but lost the ARP moly grease. As per the ARP instructions, I lubed the studs with engine oil and torqued them down to 60lbft. Some people have told me this was a terrible idea and can actually distort the gasket.

The arp instructions clearly stated to use 45lbft if using ARP moly grease, and 60lbft if using engine oil as lube.

amazingly, my boss had a brand new AF470 that's UK made and a few years old in his garage, so i whacked that on last night and torqued the ARP studs to 50lbft, with a decent calibrated torque wrench.

I cleaned up the block first, and put a straight edge on it, and both the block and the head LOOKED ok, although things like that are often very hard to tell!

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

Schrödinger's cat - so which one am I ???

is it me or have you cut the inner wing out? if so this tends to allow re-circulation of the hot air off the radiator resulting in high engine temps. i know mine is a low comp turbo but i sealed the rad to the inner wing, just run an electric fan and the temp struggles to get to "N" on very hot days and then only if stuck in traffic

On the subject of detionation, the fuel in germany i believe isnt that good, being of a lower octane. May have caused part of the problem.

Standard German UL is 91 RON, Super is 95, and Super Plus is 98, or at least it was where we went.

hmmmmmmmmmmm. I wondered why there was super, then super plus! I only ever put in the 98 ron super plus though.

got my 2 core rad last night, so I'll drop that in, then do the tappets and see how it runs!

Now seriously hoping there isn't any warping on either surface :S

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

i wonder if thats too rich for its own good ?

if the bore lubrication get washed down by the unburnt fuel ,youd get a mix of oil and petrol ,oils octane is v low ,so the mix has a greater likelyhood of detonating .

,id try at 12.5 to 1 and perhaps a bit less advance ..was the timing set with the engine at pk temps,and with the bonnet shut ?if not it may well be advanced from what the engine can cope with under thrashing conditions .

regards
robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

very interesting point robbet, I hadn't thought about the bonnet shut idea. timing was set on the rollers, with a big fan but bonnet open. the engine was up to normal temp, but nowhere near as high as it's been running lately.

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.

looks rcher (blacker) than mine and i'm running 10.5:1 afr under boost

finer droplets joe ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Right, it's running again!

Just whacked the new gasket in, and torqued everything down one last time. I also stuck in a 2 core rad I've had for years that's done less than 10 hours use.

So far it sounds a tad smoother, and most definately quieter which is odd. it warmed up to about 75-80 degrees after 30mins idling in the garage (neighbours love me!) I retroqued the head and went for a drive.

All seems so good so far. I'm going to try and take it to work tomorow, so I'll see what happens then!

Mr. Prawn, the friendly Crustacean- slowly making steps towards forced induction.