300 Tdi Rebuild

jamesmartin · Apr 11, 2017

Al2O3 said:
I'll not be taking emery tape to it, James
Have you had a chance to look at the pictures?

its not emery its proper crank polishing tape, your crank is very god but id still get it polished like the guy in the vid it gives the proper surface finish ,though yours would run for years without

Al2O3 · Apr 11, 2017

Bennehboy said:
Wish I'd seen that crank polishing method when I did my rebuild.

What did you do with yours?

jamesmartin said:
its not emery its proper crank polishing tape, your crank is very god but id still get it polished like the guy in the vid it gives the proper surface finish ,though yours would run for years without

Presumably, once you've done that, you're in to measuring journals and matching bearing shells?

Bennehboy · Apr 11, 2017

Head skim should have no bearing on the gasket thickness though, it's the piston protrusion that needs checking... unless the block deck was also skimmed??

Al2O3 · Apr 11, 2017

Bennehboy said:
Head skim should have no bearing on the gasket thickness though, it's the piston protrusion that needs checking... unless the block deck was also skimmed??

How else do you compensate for reducing the piston clearance by skimming the head?
How did you polish your journals?

jamesmartin · Apr 11, 2017

Al2O3 said:
What did you do with yours?

Presumably, once you've done that, you're in to measuring journals and matching bearing shells?

no you only get std and then +10, you take very little of just polish and refresh the surface, a better surface like with bores is better than 1/2 thou under

jamesmartin · Apr 11, 2017

Bennehboy said:
Head skim should have no bearing on the gasket thickness though, it's the piston protrusion that needs checking... unless the block deck was also skimmed??

it does if valve stand down is reduced too much

Al2O3 · Apr 11, 2017

jamesmartin said:
it does if valve stand down is reduced too much

Which protrudes the most piston or valve heads?

jamesmartin · Apr 11, 2017

Al2O3 said:
Which protrudes the most piston or valve heads?

piston sits above block face at tdi that determines head gasket thickness as long as valves are below head face by lr spec, if you skim head and valve is no longer below the spec you need a thicker gasket to put that right or you cut seats and set valves deeper in to the head, if you look at sooty piston you will see valve head imprint the run that close

Al2O3 · Apr 11, 2017

jamesmartin said:
piston sits above block face at tdi that determines head gasket thickness as long as valves are below head face by lr spec, if you skim head and valve is no longer below the spec you need a thicker gasket to put that right or you cut seats and set valves deeper in to the head, if you look at sooty piston you will see valve head imprint the run that close

Skimming the head must reduce piston clearance to valve though?
How many thou do you recon a light head skim would be? I'll call the workshop tomorrow though, just wondering.

jamesmartin · Apr 11, 2017

Al2O3 said:
Skimming the head must reduce piston clearance to valve though?
How many thou do you recon a light head skim would be? I'll call the workshop tomorrow though, just wondering.

measures depth of the valves with feeler gauges
inlet must be at least .81mm-32 thou
exhaust .86mm -34 thou

Al2O3 · Apr 11, 2017

jamesmartin said:
measures depth of the valves with feeler gauges
inlet must be at least .81mm-32 thou
exhaust .86mm -34 thou

Ok, will do.

raywin · Apr 12, 2017

jamesmartin said:
no you only get std and then +10, you take very little of just polish and refresh the surface, a better surface like with bores is better than 1/2 thou under

You would be surprised how long it would take you to reduce the diameter even 0.0005 " with fine emery as James says its more like refreshing the surface, the man polishing with Autosol is just using cloth I have used it for years it very quickly gives a mirror finish like you see in the video.

Al2O3 · Apr 12, 2017

raywin said:
You would be surprised how long it would take you to reduce the diameter even 0.0005 " with fine emery as James says its more like refreshing the surface, the man polishing with Autosol is just using cloth I have used it for years it very quickly gives a mirror finish like you see in the video.

I've got autosol, I'll polish it with that.

raywin · Apr 12, 2017

Block and head look nice, looks like they gave it a good wash better wipe some oil on the machines surfaces, should look nice when its painted.
I am still thinking of doing my TD5 either this summer or next and I was going to run a hone through it but seeing yours I may have it done and get it cleaned then paint it, was it a local company you used?

Bennehboy · Apr 12, 2017

I wanted to get mine honed by a machine shop but couldn't find anyone within a reasonable distance so did it myself with a flex-hone - bores still looked good when I had the head off a few weeks back, 2 years after doing it.

Al2O3 · Apr 12, 2017

raywin said:
Block and head look nice, looks like they gave it a good wash better wipe some oil on the machines surfaces, should look nice when its painted.
I am still thinking of doing my TD5 either this summer or next and I was going to run a hone through it but seeing yours I may have it done and get it cleaned then paint it, was it a local company you used?

Local-ish as I live out in the sticks. About 30 miles from me, which is as close as I'm going to get someone who does this work. I suppose one difference with a rebore is potential new pistons. Having said that, the pistons jump from standard, +020 and +040. So you could take a few thou off the bore before needing to jump to +020 presumably!

Bennehboy said:
I wanted to get mine honed by a machine shop but couldn't find anyone within a reasonable distance so did it myself with a flex-hone - bores still looked good when I had the head off a few weeks back, 2 years after doing it.

Mine was way beyond just being honed.

I meant want did you do about the journals on the crank?

Right, I've had a steel straight edge on the head and measured the gap to the valve faces. The exhaust valve gap is 036 and the inlet 031. So, inlet 003 out. I've bought a 3 hole gasket (one hole thicker which is 0.1mm = 004) So, all should be good.

I'll measure the upstand of the new pistons when the DTI arrives and I have the pistons installed. As they are OEM pistons I'd like to think it should all end up the same as original.

Al2O3 · Apr 12, 2017

Cheers, @jamesmartin It's been a quick learning curve this, but fascinating. Not so scary once you've thought about it for a day or two.

Another thing I've come to realise is how little gap there has to be anyway, to get the compression. Too much gap and the compression drops and so follows power loss.
If it wasn't a bit scary, it wouldn't be interesting!

I'm off to clean more engine bits, while waiting for more kit to arrive.

Al2O3 · Apr 12, 2017

Cheers, @Disco1BFG Thanks to all the advice on here, I might just be getting the hang of this.

Fingers crossed anyway

Saint.V8 · Apr 12, 2017

Al2O3 said:
Cheers, @Disco1BFG Thanks to all the advice on here, I might just be getting the hang of this. Fingers crossed anyway

Once you have done yours...I'll whip mine out (oh er misses) and send it up to you....

Al2O3 · Apr 12, 2017

Saint.V8 said:
Once you have done yours...I'll whip mine out (oh er misses) and send it up to you....

You're a very brave man

300 Tdi Rebuild

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