32 replies to this topic

[minidave54]

Hi All, I have a 1995 sprite spi and i have just replaced the head gasket (previous one had blown between cylinders 2 and 3 ). It was all torqued down according to the Haynes manual stages 1 and 2. After filling it with water i noticed that it was leaking at the front between the head and the engine. It had not been started. Took the head off again and found no damage to the gasket.

Options i am thinking about, replace the gasket and try again. Replace the studs and nuts incase they are stretched and then a new gasket?

What are people's thoughts. Any further suggestions.

[nicklouse]

I would be putting the head on with no gasket and see why it is not seating correctly.

 

studs will be fine.

[minidave54]

Nicklouse, excuse my ignorance. What would i be looking for by fitting the head without a gasket .

[Northernpower]

Did you run a straight edge across the head and across the block? Also did you remove the studs or did you just clean round them?

[minidave54]

The head was checked and skimmed the beginning of last year during a rebuild. I did run a straight edge across the block and found nothing obviously wrong. The studs were not removed, i just leaned around them. Would you recommend removing them to clean the engine mating surface?

I do find it odd that there was not a water leak with the previous gasket, just a compression loss between 2 and 3.

[Northernpower]

The head was checked and skimmed the beginning of last year during a rebuild. I did run a straight edge across the block and found nothing obviously wrong. The studs were not removed, i just leaned around them. Would you recommend removing them to clean the engine mating surface?

I do find it odd that there was not a water leak with the previous gasket, just a compression loss between 2 and 3.

Its not right because if you had the head skimmed last year during the rebuild and you assembled it correctly it would not blow. If you're confident the head was skimmed correctly you need to focus your attention on the block. If it were me I'd remove the studs and run a surface plate with some fine wet and dry across the the top of the block.

[minidave54]

I do not have access to a surface plate. Would a straight edge and fine wet and dry serfice ?

[Northernpower]

I do not have access to a surface plate. Would a straight edge and fine wet and dry serfice ?

Unfortunately not, it needs to be something more substantial. Did you change the head studs, nuts and washers when you had the head off the last time?

[minidave54]

It was just the nuts that were changed. I did wonder if the threads of the studs could be stretched. But would this cause the water to leak out after the head being torqued down.

[Northernpower]

It was just the nuts that were changed. I did wonder if the threads of the studs could be stretched. But would this cause the water to leak out after the head being torqued down.

I may well be part of the cause but its pointless speculating until you establish the state of the top of the block. You'll definitely want to renew the studs, washers and nuts when you rebuild this time.

[neal]

If your old head gasket fire rings failed between cylinders 2 & 3 causing loss of compression, an excess amount of heat would have been apparent in that localised area whereas the rest of the cylinder head face and block would be at a more consistent temperature.

 

This could cause warping of the block face and/or cylinder head face so I would have checked it diligently with a good quality straight edge and a set of feeler gauges to see, if so, was there any of warp and how many thousandths of an inch did you measure?

 

Was there any signs of fretting of the threads (raised burrs protruding) into the cylinder block protruding proud where the studs are screwed in?

 

Did you refit using a good quality head gasket when it leaked?

 

Did the coolant leak at the front from the joint faces of the head and block between cylinders 2 & 3 or is it leaking towards the end of the cylinder head?

 

So many things to check and consider. It could even be a bit a crap that dropped as you were putting your head back on.

Edited by neal, 28 April 2017 - 05:55 PM.

[RooBoonix]

I had exactly this problem. The problem was with the gasket supplied in Minispares SPI head gasket kit (BK450 maybe, but I'm not sure), I couldn't find anyone else who had this problem. The head had just been skimmed and I used brand new studs and nuts. 

 

Using a new gasket fixed my problem, I used a Minispares GEG300, and that's what I'll be using again when I build my engine up during the week.

[Magneto]

Last remark, did you re-torque the head the last time you changed the gasket? I always do this, run it up to temp, let it cool down cold then re-torque all the nuts and recheck the valve clearances.

[sonikk4]

Was it a copper gasket or a Payen gasket??

[nicklouse]

Nicklouse, excuse my ignorance. What would i be looking for by fitting the head without a gasket .

It makes very easy to see what is possibly stopping the two surfaces coming together correctly.