Head gasket failure / theory / question thread

[RustyNuts]

Hi all

 

So I did a swapover of the safrane engine as some of you may recall. After some running with just water in it and accidentally letting it get to 3/4 of the gauge (not normally a problem) I noticed some white mayo on the oil cap. It's not a lot but definitely enough to make me think this engine wasn't going to live long anyway - it had been stored 3 years with no coolant in the engine.

 

So.. something came back to me the other day about a steam engine programme on TV. Steam takes 1000 times the volume of air apparently and what with coolant increasing the boiling point of the water it's mixed with it suddenly dawned on me that there has probably been a build up of steam inside the block which would then (under sheer pressure) have breached the head gasket. 

 

Is that theory correct?

 

A lot of folks have mentioned it'll be condensation but these engines don't typically suffer with it (I left one 14 months before running it and it had no symptoms of mayo) and in the warmest part of the year I'm just wondering how condensation would have managed to build up in there?

 

Thanks for your time,

 

Rusty

 

[dave21478]

I wouldnt be doing a damn thing to it until I had taken it for a proper run of at least 10 miles and made a real diagnosis instead of supposition and guesswork.

[oldcars]

Did you fit a new unknown engine in the car? When my headgasket went on the Reliant there was very little oil in the water. I flushed the cooling system with water once the head was skimmed and a new gasket fitted. It took a few months for the oil to get out of the cooling system. I had a little oil on the radiator cap but now i have none. I do have a little mayo on the oil filler but i put this down to short runs. Your may be ok, have you tried driving it yet?

[scaryoldcortina]

Steam can't build pressure in the block because it's vented. Also, my TF continued to spit bits of mayo onto the dipstick and cap even after a full teardown and new HG followed by a flush through with diesel before the oil went in. It's now clear but it took almost 1000 miles of thrashing. (what a chore...)

 

 

^ That's what serious HGF does to your oil...

[twosmoke300]

Exactly - you are overthinking this . It can take many miles to burn off any moisture in the sump etc . 

My wifes ER5 would make the oil go totally milky in the winter unless it did 30 miles a day . Never used a drop of coolant over 40,000 miles like that .

 

Get it out and give it a good hard road test before you get all technical about it all

 

Oil in the water is deffo HG / Oil cooler issue but water in oil can be something much less sinister

[steveo3002]

there wouldnt have been steam inside thats what the breathers are for

 

take it for damn good run and change the oil...see how it is then

[Vince70]

I had an old RTi Laguna 4 pot (is it the same engine minus a cylinder ) and it always had a bit of mayo on the dipstick tube and sometimes on the filler cap and It never went away completely.

 

It never used a drop of coolant and went on for a good few years after I got rid of it plus we had the car in the family for 5 years like that and it was always the same apart from maybe once on a Saturday in August sometime lol.

 

I would use the safrane for a bit and give it a couple of oil changes as it really is the the only way to find out.

 

Come Autumn till spring I know that one of my BMWs will do this as its done it every year since I've owned it and the engine is fine, I think some cars are just more susceptible than others as I have the same engine in another car and it never has suffered condensation issues.

 

Funny thing is my girlfriends father had a talking 25 for years when they first came out and apparently it would tell them it was about to grenade due to overheating problems but never did.

Her earliest recollection of being in a car as kids was always being terrified of going on holiday in the family car knowing it was going to tell them to abandon ship quickly and her dad not taking any notice of the cars computer.

[dome]

 you to run it properly before deciding it was definite HGF?

 

 

 

there wouldnt have been steam inside thats what the breathers are for

 

take it for damn good run and change the oil...see how it is then

 

 

Exactly - you are overthinking this . It can take many miles to burn off any moisture in the sump etc . 

 

Get it out and give it a good hard road test before you get all technical about it all

 

 

 

 

 have you tried driving it yet?

 

 

I wouldnt be doing a damn thing to it until I had taken it for a proper run of at least 10 miles and made a real diagnosis instead of supposition and guesswork.

 

I think we can safely say we are all in agreement here.

 

Get the cooling system bled up properly and then drive the thing. 

 

It will take a good long run to get the condensation out of it, especially if the engine has been sitting about. 

 

Don't worry until it shits itself spectacularly.

 

When it does, post pics

[Bobthebeard]

I think we can safely say we are all in agreement here.

 

Get the cooling system bled up properly and then drive the thing. 

 

It will take a good long run to get the condensation out of it, especially if the engine has been sitting about. 

 

Don't worry until it shits itself spectacularly.

 

When it does, post pics

Agree...

You are definitely over thinking this. Just drive it. Nothing to lose really. Probably just condensation as mentioned.

[They_all_do_that_sir]

Whack some proper coolant in and get some miles on the thing. Tbh even if there was a bit of mayo I wouldn't care in the short term as long as it's not losing coolant and the heater does its job.

 

Sent from my D6603 using Tapatalk

[beko1987]

the meriva has constantly changed up breather pipes, I have to scrape the main sump breather out sometimes, especially over winter.

 

it's mainly because it does about 40 miles a week, and frequent journeys of 5-6 miles and its never used a drop of coolant, or more oil than it should. winters coming, it'll do the same again. I leave one of the small breather pipes uncapped now so it it gets bad it pops off and I can check everything rather than it bunging up and not telling me

 

her old corsa 1.2 was worse, proper mayo type stuff everywhere, I took the cam cover off and Mr muscled it clean, was fine when I started driving it to work and caning it for 26 miles a day!

 

drive it ffs. put water in rather than coolant, and cheap oil to start, if its fine after a week, change to coolant/nice oil!

[RustyNuts]

Hi Guys..

 

I think you're misunderstanding my point. I was asking the theory of how the overheating affects the headgasket in order for it to be breached. I'm not so worried about this engine but more the theory of how to avoid it happening again - IF (and thats only IF) this engine is dudd.

 

But yeah.. it would be nice to know if my theory is right / wrong ..

[RustyNuts]

Steam can't build pressure in the block because it's vented. Also, my TF continued to spit bits of mayo onto the dipstick and cap even after a full teardown and new HG followed by a flush through with diesel before the oil went in. It's now clear but it took almost 1000 miles of thrashing. (what a chore...)

 

 

^ That's what serious HGF does to your oil...

 

Hang on that reminds me... when you say vented do you mean the tank cap? - that rings a vague bell now..

 

As for the failed HG oil... yes i've seen that before.. and yes i had similar to the above come out of the old engine when i removed it.

[scaryoldcortina]

Engine is vented by the crankcase breather system, if it wasn't then the pumping effect of the backs of the pistons would pressurise it and force oil out everywhere.

 

As to causes of HGF, there are several, and also several different sets of symptoms depending on the type of failure.

 

First - water into oil/oil into water. K series engines are good at this, basically overheating causes the gasket to breach between a waterway and an oil gallery (around one of the head bolts is usual) and this lets water into the sump first as a slow leak (mayo, mystery water loss) and then as a big fail where your water bottle ends up empty and your oil pump is pumping coolant around the bearings. New HG usually sorts this.

 

Second - Compression into water - either a failed firering or severe overheating allow combustion gases to escape into the waterways instead of pushing the piston down. Symptoms are brown nasty smelling water that "boils" when you rev the engine. Much harder to fix properly on a modern, but you'd get away with it on a pinto.

 

Third - breach between cylinders - the firering fails allowing gases to pass, symptoms are loss of compression on two adjacent cylinders. Water and oil are likely to be fine. Fiat Puntos do this quite a bit.

[Dead_E23]

Differential expansion of dissimilar materials and/or warpage.   That'll screw it!  

 

Steam pressure seems somewhat less likely; if the gasket holds less pressure than the spring on the radiator cap I'd say there's already a problem.

[drum]

Scrap the safrane and buy a car on pcp.

 

 

 

 

 

 

 

 

 

 

 

 

Just kidding...

[RustyNuts]

Engine is vented by the crankcase breather system, if it wasn't then the pumping effect of the backs of the pistons would pressurise it and force oil out everywhere.

Yes I understand that part.. but how would that help potential steam to escape if the coolant area and combustion chamers are seperate? - I can understand the engine breathing and recirculating oil vapour but surely the coolant itself does not share this breather system?

 

basically overheating causes the gasket to breach between a waterway and an oil gallery (around one of the head bolts is usual)

Thats what I'm trying to get at. How does this occur? - Is it steam forcing things apart (IE once the max temperature of the coolant chemical is exceeded) or do the bolts just stretch and allow the head to follow???

[scaryoldcortina]

I thought you were talking about steam in the block, not the waterways... my bad!

 

 

It is possible for a plug of steam to develop in the head that can't escape, either because of air in the pipes or someone letting the cap off a hot engine. That can breach a gasket, particularly if it's been optimistically engineered from the back of a biscuit tin and some bathroom silicon like the one in the picture.

 

PS, don't assume your engine has done that. I agree with everyone else when they said just run it and see what happens.

[RustyNuts]

Ah so there is something in my way of thinking then! Sorry I didn't make myself clearer - the word waterways escaped me.

 

Thanks for your help

[Station]

Put a dehumidifier in a dry room and it'll still suck water in. If you've ever dropped a single water droplet into a pool of oil and scrubbed it in with a brush (and I mean, who hasn't done that, eh?) it turns into that mayonnaise stuff. Water vapour is a byproduct of combustion so I'm told.

My theory is your inlet may have collected water vapour over time and it's gone straight into the sump through the cylinders.

[Noel Tidybeard]

3/4 on the temp gauge ist really overheating anyway- right in the red is when to worry big time

 

my renner 19 has a "normal" operating range of between 1/4- 3/4 accoring to the manual

[twosmoke300]

You will need to get the oil temp above 100 degrees for a good time to boil off the water vapour present in the oil

[steveo3002]

would have cost too much to give the new engine a freshen up while it was out ?  

[garbaldy]

Ah so there is something in my way of thinking then! Sorry I didn't make myself clearer - the word waterways escaped me.

 

Thanks for your help

 

I really can't understand how you expect steam to build up inside the block when it's full of water, if you half fill the cooling system with water that may produce steam but it will vent through the cap way before the pressure required to pop a head gasket.

[RustyNuts]

would have cost too much to give the new engine a freshen up while it was out ?  

 

It's not been out yet mate - car is still up on the stands waiting for permission for me to finish it. I had hoped to put it in for an MOT TODAY but seeing as the fucking lergy decided to infect me again - less than a week after fighting it off, i'm a bit buggered.

 

EDIT - I thought steveo meant taking the car out - Im a prat!

[Dave_Q]

Volume is not the same as pressure, the coolant system is limited to approx 1.5-2 bar pressure after which any excess is vented via the rad cap etc.

 

The in cylinder pressure is more like 80-100 bar. 

 

Generally gasket failures are caused my imperfect (rusty/not flat) sealing surfaces, either from the factory or developed over time by rust etc. 

 

The gasket material can also degrade over time, especially if made of B&H foil and chewing gum as per SOC's pic.

[RustyNuts]

would have cost too much to give the new engine a freshen up while it was out ?  

 

Ignore my previous, i  thought you meant take the car out - i'm clearly stupid.

 

I didn't really have any spare money for the engine or else i'd have done the gasket on the original engine so this one has gone in without so much as a cambelt change. Yes thats madness but i knew one old fella with 180kk on the clock without a belt change.

 

I just need it to pass an MOT so 'er indoors stops giving me greif about it.

[steveo3002]

hmmm if moneys tight then so be it ....but man id have done it while it was out , did you check if amazon has bargain bits , was selling some stuff for a few quid the other day

[RustyNuts]

To be honest I'm not really phazed about it... if it gets through an MOT then I can justify the money and hassle without being nagged at too much. Without that, it's just adding fuel to the fire.

 

But I will take a look at amazon..