26 replies to this topic

[Big_Adam]

Afternoon.
 
I have only done ... 4 head gaskets in my life time. They seem to be holding up and I need to do a 5th soon (all different cars here).
 
I looked up how to change the head gasket for a Pug 106, and was happily watching when I say the guy take sand paper to the block and head.


About the 14min mark.
 
My thinking has always been, any dirt / grit in the engine means the engine will eat itself alive. The head gaskets I've done before, I tended to take the gasket off, then scrap off whats left. I've never taken sand paper to the block or head.
 
I checked some other youtube videos and it seems a done thing. They always just say sand paper, which seems insane to me. As sandpaper, to me automatically means a bit of paper with sand glued to it.
 
Wouldn't the grits fall into the engine and kill it?
 
How do you good folks go about it?
 
Or am I just being too overly cautious when thinking about grit in the engine?
 
Ta for any advice/input.

 

Edit

 

Also anyone know a decent glove to keep my hands warm when wrenching on stuff? Just in general.

Edited by Big_Adam, 29 January 2014 - 05:36 PM.

[Alex_B]

I personally would never start sanding the head or block face, if its not perfectly flat then it should get machined flat at an engineering shop using properly calibrated machines, and this would require the head or block to be properly cleaned to remove any swarf as you say it could damage internal components 

[Craig89]

I use a fine grit emery paper not sandpaper, as you say you wouldn't want bits of sand in the area, when cleaning the gasket surfaces of both the block and head. When doing the block I tightly fill the bores with rag/paper to ensure nothing goes down the bores. After cleaning the surfaces I thoroughly blow out everything with compressed air

[1984mini25]

Fine wet and dry with wd40 should be ok.

[KernowCooper]

For every qualified engineer there are 10 not! Wet and Dry is a world of difference away from Sand Paper unless they don't know the difference

[Big_Adam]

I personally would never start sanding the head or block face, if its not perfectly flat then it should get machined flat at an engineering shop using properly calibrated machines, and this would require the head or block to be properly cleaned to remove any swarf as you say it could damage internal components 

 

See, thats my thinking too on the internal damage. Bit of grit travelling around the engine eating components alive.

 

I use a fine grit emery paper not sandpaper, as you say you wouldn't want bits of sand in the area, when cleaning the gasket surfaces of both the block and head. When doing the block I tightly fill the bores with rag/paper to ensure nothing goes down the bores. After cleaning the surfaces I thoroughly blow out everything with compressed air

 

But what about grit in the oil ways then?

 

Fine wet and dry with wd40 should be ok.

 

How fine we talking here?

 

For every qualified engineer there are 10 not! Wet and Dry is a world of difference away from Sand Paper unless they don't know the difference

 

I'm getting different answers from everywhere so far. Some people (from google searching) saying use scotch bright pads, some saying just use scrapers. Hence my confusion.

[KernowCooper]

Fine wet and dry paper has been used for years, and the process of using it to clean up the block face used correctly does not really cause issues, but its in the application, where as rubbing with rough paper and pints of fluid running everywhere is a different matter.

 

Which comes back to training and experience, and where there is a block face or cylinder head which needs cleaning up, anymore than cleaning needs checking for refacing.

[Big_Adam]

Fine wet and dry paper has been used for years, and the process of using it to clean up the block face used correctly does not really cause issues, but its in the application, where as rubbing with rough paper and pints of fluid running everywhere is a different matter.

 

Which comes back to training and experience, and where there is a block face or cylinder head which needs cleaning up, anymore than cleaning needs checking for refacing.

 

Well, how fine a paper are we talking here? I got 60, 120, 180 and 400 to hand.

[sledgehammer]

I use a gasket scraper , then wipe with thinners , light pressure fine wet/dry if necessary 

 

& blow around pistons with air line once all the gasket removed

 

clean the threads on the studs

 

also check the gasket for bits stuck to it - sometimes the varnish is tacky

 

after torquing to the manual - I run for a few mins without water , to help the varnish cure

 

then re-torque when specified & fill with coolant

Edited by sledgehammer, 29 January 2014 - 06:28 PM.

[KernowCooper]

I use 500 wet and dry the others you have are to course.

[Big_Adam]

So the general conciseness then is.

 

Remove head, scape off as much as possible, clean with 500+grit paper, new gasket, head, torque and change oil afterwards to get rid of any nasties then floating about.

 

sound about right?

[Alex_B]

you shouldnt have much of an issue with 500 grit use it on a perfectly flat block, and dont sand in one single direction, you wouldnt want to find its no longer a flat block/head surface 

[Gremlin]

In your first post you said 'Am I being over cautious' Answer - you can never be overly cautious about engine hygiene

[Fast Ivan]

you can never be overly cautious about engine hygiene

 

that's one of the best phrases ever

[Cooperman]

Emory cloth is better than wet & dry and it's what many use on the head.

To do the block all the head studs need to be removed and the bores, oil way holes and coolant holes blocked first.

The emory the surface with the sheet of emory on a flat block around 6" x 3" until all the surface is clean.

If fitting a copper faced gasket use a smear of light oil on the gasket faces, but if fitting a BK450 'black' gasket, which is the best, don't put anything on the faces.