9 replies to this topic

[Rubbershorts]

Hi everyone.

Quacking with the car today identifying the TDC. As this involved having a look down no.1 cylinder I poked the little camera down to watch for it's progress. The crap on top of that piston was a bit worrying. There was actually one flake that was loose. I used a small disposable pipette to try get it near the plug hole to maybe lift it out, but lost it. I don't know if it looks worse than it is as the bores were quite flooded due to recent starting issues.

What do you guys think?

I'm thinking of changing the head gasket soon, as I seem to have an oil leak at the back of that no.1 cylinder, could the two things be related? Other cylinders were a lot better.
I'm not experiencing any other blown head gasket symptoms, that I'm aware of. The pic of the rockers is too show how clean they are.

Thanks,Daz.

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[gazza82]

Probably carbon build-up from normal use but if you've flooded the engine or put fuel/oil down the bores then the residue will be soaked.

If you are planning to change the head gasket, then expect to also do a "de-coke" ... there are right and wrong ways to do that too!

[sledgehammer]

Combustion is a dirty business , so I think the piston crown is ok IMHO

 

flaky bits , will build up , and are normally expelled thru the exhaust

On a lot of pistons you can see where bits have broken off and are no where to be found

if you can get a flaky bit out - all the better . 

 

the oil leak  , is probably a small rivet , blocking the  oil cross drilling at the back of the head (not a normal rivet - a hydraulic plug)

 

I've got a similar problem on my head - but it is only a slight weep

 

the rivet / plug can sometimes be drilled out , and tapped to accept a grub screw ,

on some heads that have been reworked , the oil way is close to the head surface , 
 

on some 1275 heads the drilling is at the top IIRC so it isn't a problem - (my memory is bad- maybe a different engine)

[Lplus]

The oil feed to the rockers passes through the gasket in the back corner next to No 1 cylinder.  If the leak is from the head/block joint it might be the seal is failing there.  Unlikely to be related to the carbon in the bore though.

 

Have you checked the head nuts are to torque?

[Rubbershorts]

Probably carbon build-up from normal use but if you've flooded the engine or put fuel/oil down the bores then the residue will be soaked.

If you are planning to change the head gasket, then expect to also do a "de-coke" ... there are right and wrong ways to do that too!

Thank Gazza. A decoke? Something else I've got to learn. Don't remember seeing that in the Haines. How would I do it?

[Rubbershorts]

Combustion is a dirty business , so I think the piston crown is ok IMHO
 
flaky bits , will build up , and are normally expelled thru the exhaust

On a lot of pistons you can see where bits have broken off and are no where to be found

if you can get a flaky bit out - all the better . 
 
the oil leak  , is probably a small rivet , blocking the  oil cross drilling at the back of the head (not a normal rivet - a hydraulic plug)
 
I've got a similar problem on my head - but it is only a slight weep
 
the rivet / plug can sometimes be drilled out , and tapped to accept a grub screw ,

on some heads that have been reworked , the oil way is close to the head surface , 
 
on some 1275 heads the drilling is at the top IIRC so it isn't a problem - (my memory is bad- maybe a different engine)

Thanks Sledgehammer. I think I've located the rivet, as I'd read about it previously. It's higher up than my leak, and bone dry.

[Rubbershorts]

The oil feed to the rockers passes through the gasket in the back corner next to No 1 cylinder.  If the leak is from the head/block joint it might be the seal is failing there.  Unlikely to be related to the carbon in the bore though.
 
Have you checked the head nuts are to torque?

Hi LPlus. Before I saw the debris on top of the piston I was going to look into a re torque of the head bolts. May as well dive straight in a learn something else and kill two birds with one stone. Do some re search on what a de coke concerns and change the head gasket. Gasket change seems relatively straight forward, but is there anything I shouldn't do? Pitfalls? Daz.

[bpirie1000]

How did it run?

How did plugs look?
Mixture may be an issues

[Lplus]

 

The oil feed to the rockers passes through the gasket in the back corner next to No 1 cylinder.  If the leak is from the head/block joint it might be the seal is failing there.  Unlikely to be related to the carbon in the bore though.
 
Have you checked the head nuts are to torque?

Hi LPlus. Before I saw the debris on top of the piston I was going to look into a re torque of the head bolts. May as well dive straight in a learn something else and kill two birds with one stone. Do some re search on what a de coke concerns and change the head gasket. Gasket change seems relatively straight forward, but is there anything I shouldn't do? Pitfalls? Daz.

 

If the head bolts are not to spec, tighten them and use the car for a bit before removing the head, to see what difference bolt torque makes if any.

 

As to pitfalls, I think some people say not to clean around the top of the bore and the edges of the pistons to ensure any seal is maintained.  I also put grease around the piston/bore gap to try to stop crud getting down the gap.  Not sure if it really helps but there you go.

 

Also make sure the mating faces are totally clean and dry.  Others may well be along with other ideas.

 

 

Personally, I'd use the car for a bit now it's going and see how it performs before ripping more of it apart.

[Rubbershorts]

How did it run?



How did plugs look?
Mixture may be an issues

The plugs were a bit black and soaked in petrol but that was due to the continual turning it over trying to get it started after the above mishap. Prior to that they were pretty good.

Edited by Rubbershorts, 18 November 2024 - 05:17 PM.