Technical Blown head gasket - But I can't find where?

[DmanF1]

Hiya,

Purchased a MK1 75sx a few months ago and fell in love with its simplicity etc. Then a few weeks ago an overheating problem that went real bad got me to a garage for diagnostics. They said they did a water test and the head gasket had gone :bang:

Well, since the garage was talking about £400 and I only purchased the car for £470 I thought to hell with it, lets do it myself :slayer:

Now I love cars, but im no mechanic, the most advanced thing I did was change spark plugs. Yet this brilliant site has really helped me with guides etc and today I finally got the damn head off

The thing is, I wanted to have a look at the gasket to see what went wrong. On inspection, the water channels are severely gacked up with rust coloured crap. However, I cant visually see any cracks between a cylinder and a port, nor any visual path showing how the water got into the cylinder

I will try and get a pic tommorow, but Im really confused. Obviously there is a leak hence the gack (and the severe white smoke out of the exhaust). But how is the water getting in?

One theory I had was becasue the gack was so bad, (It wasnt flushed with the gasket) it could have caused a small pocket somewhere. But then the gasket has to fail for the gack to form?!

I really dont want the answer to be a warped block guys! It looks okay I aint cleaned it yet. Your thoughts????? :idea:

The head should be going to get machined in the week...

 

[PuntoHowTo]

Post pic of both sides of the gasket and I'm sure some one (if it's there) will spot the leak in no time

 

[fingers99]

I don't trust "sniff" tests. I don't like sniff tests. I don't do sniff tests.

Why? Because all they can do is check for the by-products of combustion in the coolant. I suspect all they're checking for is acid. Lots of ways that can get/remain there. They're expensive for what they are and don't give you any further diagnostic information on the condition of the engine. A monkey could -- and often does -- do them. Compression tests rule.

Chances are that the HG has simply blown and/or the head warped. A warped block is extremely rare (although one that hasnt had the mating surface cleaned properly is not uncommon) and cracked heads are very rare in FIRE engines (FIAT make damn good castings).

 

[DaveMcT]

Now the head is off its really not relevant where the gasket failed. The valves need to come out and the head joint face should be lightly skimmed (at a machine shop) to be sure the joint is clean.

When its all back together, chemical flush the cooling system with something like Radflush. It may well show up leaks elsewhere but better to know - and fix the problem before the new gasket gets fubared.

 

[bredsticz]

My gasket had split sideways when i took mine out. so wouldnt see it looking at either face. Slightest little hole can cause it though

 

[s and b]

i posted up some photos a few weeks back the metal ring on the edge of the head gasket that crushes when tightened down had broken very slightly and was allowing a very very small amount of water into the combustion chamber and was coming out as white smoke
it never got no worse
and it was very hard to see on the gasket
a vacuum test was steady as a rock and good figure at 18
a sniff test might have shown it but the water jacket was only very very slightly pressurising so it might not have
a good clean of head and block one new gasket thrown in and the car is perfect again
took 4 hours all up

 

[DmanF1]

Thanks for your help guys.

Well, here are the pics. Money is tight, so Im going to wait for 2 weeks before I get paid so I can get the head skimmed and put it back together that weekend. Going to give the surfaces a good clean in the meantime.

In regards to taking out the valves, the skimming shop told me I can leave them in (because its non interferance). I don't have the tools to remove the springs and Im not keen on setting the valve clearances.

I dont really want to take the camshaft out as well unless I have to. I haven't asked the shop yet but I might see if I can pop the rocker cover back on and they can put it through the machine like that. I plan to remove those pesky stud bolts and also the thermostat today.

Anyway, here are the pics. I gotta say, as a first time experience of getting my hands really dirty, I have learned a lot with this lovely little engine

I just hope she is fine once I put back together

*NOTE some of the water ports were nearly blocked over by the rusty coloured gack before I took this pic...

 

[fingers99]

Valve clearances are easy to do. But it's best to get the valves recut first. No engine will run well with incorrect valve clearances or a poor seal between valves and valve seats.

A radiator flushing compound in the coolant, after rebuild, followed by a flush ot two, will clear most of the rist from the rest of the cooling system.

 

[DmanF1]

I just have had a bad experience with that radweld stuff from halfords. Few years ago I used it on my bmw and the thermostat dislodged and put massive pressure through the system. Think the punto does need a good flush though.

 

[fingers99]

Radweld does the opposite to a flushing compound, though.

 

[DmanF1]

The stuff I used was one flush agent and one radwell similar thing for filling holes. Thing is the thermostat is renound on the E36 3 series to be flimsy and has crappy plastic mounts that break. It was probably the fact there was flowing water rather than the chemicals in the agents.

The radiator bent like a banana! The garage said he wouldnt be suprised if the gasket failed as well, but apart from a new thermistat and radiator it was all good

 

[s and b]

back to the punto
im surprised no-one has mentioned the picture of the headgasket you posted up
it has all the classic symptoms of poor maintainance in the antifreeze dept
the whole circle has rusted and the holes in the head and block are in a terrible rusty state
i would be thinking very carefully if this was my car because things like thermostat water pump and both matrixes are probably not far behind in giving up the ghost

 

[DmanF1]

thanks. The thermostat has got a lot of white crusty crud all over it so I do think changing it is a serious consideration. Unfortunately one of the bolts of it is not coming off. I'm going to try some wd40. Do you think putting the head in my vice and attacking the bolt with a spanner and a hammer is a bad idea? Is the head and valves sensertive to that sort of violence? Most of the stud bolts are stuck tight as well. I've tried the two nut trick and its worked on a few. Something to keep me occupied for a couple of weeks before skimming anyway!

 

[s and b]

if you have a mig then weld a nut onto the thermostat bolt once you have it off,this will make heat go down the bolt into the head and will likliest then easily undo
yes do as you say if you dont have a mig
you could also cut the thermostat housing off round the nut too as the housing comes with a new thermostat
dont forget to flush radiator and hoses if you can and it might be a good time to replace the water pump if you are not intending using the old timing belt so you dont take bottom pulley off
one more thing the bolts holding engine mounting to the engine are very tight,make sure you have a good fitting socket before you try undoing them so you dont burr the heads up

 

[fingers99]

For the studs -- removal isn't "really" necessary.

The 2 bolt trick will eventually work, but can be assisted with a "real" penetrating oil -- GT-85, PlusGas, etc. -- heat, or (the studs are pretty cheap, but don'r take my word for it) welding a bolt on.

 

[DmanF1]

For the studs -- removal isn't "really" necessary.

The 2 bolt trick will eventually work, but can be assisted with a "real" penetrating oil -- GT-85, PlusGas, etc. -- heat, or (the studs are pretty cheap, but don'r take my word for it) welding a bolt on.

I dont have a mig. But also, the only reason I am removing the studs is I am assuming the machine shop will need them out to put them on their machine. They have already told me I can leave the valves in - I am assuming I can keep the camshaft in as well if thats the case? I will probably give them a bell on Monday just to check...

Im not changing the cambelt as a new one was fitted in September. I removed the tensioner to get the belt off (which was a nighmare as it was done up super tight). In regards to the engine mounts, I did consider unbolting when I had difficulty getting to the tensioner but in the end I got a spanner in so left it.

 

[fingers99]

Leave the studs in, shouldn't be an issue for them.