Finding and preparing a new to me AMF

Measuring piston protrusion, I've since found a slightly better setup that I will post when I get the final measurement.

Tools designed for the job holds the dial gauge perfectly vertical above the block and piston. Either the VW tool in an illustration above or a beam for the gauge with two precision legs. I made do with the tools I have:

Set the gauge to zero on the block.

IMG_0862.JPG


Move the gauge over the piston and advance the crank until the gauge reads zero. Check the piston top is level with the block with your fingers, slight discrepancies are easy to feel.

IMG_0863.JPG


Once you are satisfied zero on the piston is level with the block advance the crank so the piston reaches the top of its stroke. The dial looks the same but it has advanced by 1.03 mm. The protrusion of the piston can be seen.

IMG_0864.JPG


1.03mm is bottom tolerance for a two hole head gasket. A two hole came off the engine but unfortunately the part number has gone.

IMG_0865.JPG


This is just an interesting aside and I will do the job again more thoroughly with a much cleaner block. I've noticed something far more interesting: does anybody have the head off of a diesel? I'd like to compare a characteristic that I have spotted. Thank you.
 
philward said:
Measuring piston protrusion, I've since found a slightly better setup that I will post when I get the final measurement.

Tools designed for the job holds the dial gauge perfectly vertical above the block and piston. Either the VW tool in an illustration above or a beam for the gauge with two precision legs. I made do with the tools I have:

Set the gauge to zero on the block.

View attachment 116432

Move the gauge over the piston and advance the crank until the gauge reads zero. Check the piston top is level with the block with your fingers, slight discrepancies are easy to feel.

View attachment 116433

Once you are satisfied zero on the piston is level with the block advance the crank so the piston reaches the top of its stroke. The dial looks the same but it has advanced by 1.03 mm. The protrusion of the piston can be seen.

View attachment 116434

1.03mm is bottom tolerance for a two hole head gasket. A two hole came off the engine but unfortunately the part number has gone.

View attachment 116435

This is just an interesting aside and I will do the job again more thoroughly with a much cleaner block. I've noticed something far more interesting: does anybody have the head off of a diesel? I'd like to compare a characteristic that I have spotted. Thank you.
Click to expand...
Block or head?
 
philward said:
Bump, anybody got the top off of a diesel and doesn't mind posting what they see in the bores compared to the engine I have? I'll get some pictures later.

I think I have bore polishing or glazing to deal with. This article relates to boat diesels but explains both characteristics http://coxeng.co.uk/engine/bore-glazing-and-polishing-in-diesel-engines/#:~:text=Bore glazing occurs at low,warn against the potential problem.
Click to expand...
Are you going down a total engine strip route If so you could have it lightly rebored etc,
Although more cost effective route would be to re-hone the bores to give the required cross hatching in-situ & the pistons at their lowest point, suitably protected from dust ingress etc would give the required cross hatching.
 
kp 115 said:
Are you going down a total engine strip route If so you could have it lightly rebored etc,
Although more cost effective route would be to re-hone the bores to give the required cross hatching in-situ & the pistons at their lowest point, suitably protected from dust ingress etc would give the required cross hatching.
Click to expand...
I didn't want to be in full strip down territory, it's the reason I waited for a low mileage engine. However I think the rings are shot on cylinder three. I'll get some garage time later so will post pictures after.
 
This is my first major job on a diesel engine, I have rebuilt petrol engines but I have no recollection of pistons moving like this:


There is a knocking sound but the pistons do not touch the bores. When pushed towards the back of the engine the gaps between the piston and bore are 0.45mm max and .08mm min.

The bores are very shiny and there is not much evidence of honing. Wear is minimal though with a tiny ridge at the top of the rings stroke:

IMG_0882.JPG


Those of you with diesel engine experience, would I be looking at bore glazing and ring wear or is this normal?
 
Woukd imagine some play is normal to get sprung piston rings in. Interesting to see this, look forward to a good answer. My complete lack of knowledge on the subject is evident but I'd guess it should be harder to move?? Also wouldn't see why it would be different to a petrol piston in terms of movement
 
philward said:
This is my first major job on a diesel engine, I have rebuilt petrol engines but I have no recollection of pistons moving like this:


There is a knocking sound but the pistons do not touch the bores. When pushed towards the back of the engine the gaps between the piston and bore are 0.45mm max and .08mm min.

The bores are very shiny and there is not much evidence of honing. Wear is minimal though with a tiny ridge at the top of the rings stroke:

View attachment 116650

Those of you with diesel engine experience, would I be looking at bore glazing and ring wear or is this normal?
Click to expand...
Looks like you need to measure the internal bores accurately in multiple places on each bore
with an internal micrometer,
may need new rings if out of tolerance.
 
kp 115 said:
Looks like you need to measure the internal bores accurately in multiple places on each bore
with an internal micrometer,
may need new rings if out of tolerance.
Click to expand...
That is consistent with advice I’m getting elsewhere. Best case scenario is a hone and new piston rings.
I’m learning about diesel engines, this engine is lowish milage but has probably lived its life in a busy town where it has spent too much time idling. Probably going to make one engine out of two. Didn't get an easy fix I wanted but should make for a more interesting thread.
 
kp 115 said:
Interesting big ends exposed what’s the condition?😳
Click to expand...
The crank and conrod bearings look quite good but I’ve yet to clean up. Will measure and report, probably in the New Year.
If I have a problem it is the bores and piston rings. The oil control ring on 3 fell apart on the way out.
 
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