Perkins P3. 144 Engine question/s

[Welderpaul]

Thanks to a forum member my enthusiasm in this is realighted. You know who you are

I rebuilt this Dexta engine a while ago, but now knowing a bit more, i've opened it up to check tolerances before I finish it off and send it.

First off the bores - i've measured them and checked against the original book. These are the original liners (Original to me anyway), when i originally stripped it i took off the ridge at the top of the bores and put new piston rings on. The bores feel smooth, no nasty ridges etc.

It seems to be a massively tight tolerance in the handbook, and of course the liners have worn, but is this wear enough to warrant pushing the liners out, replacing and machining?

 

[m_c]

It all depends on how much effort you want to put in to it.
It will likely run perfectly fine the way it is.

However, is that pitting in No.1 bore?

 

[Welderpaul]

No it’s staining. There are marks on no 3. They almost look like centre pop marks. Spanner for scale. Problem?

 

[frank horton]

Ok for starters.....
can u still feel a lip with ur finger nail at the top of the bore......?
how much of a lip was there and what did u use to remove it.....?
did the engine ever run with those pistons.....?
.......
normally if there is a decent lip I replace the liners and pistons, every time......quite cheap......
those liners should be deglazed/honed before rebuilding esp with new rings......
if there is a slight lip u can buy a set of rings with what's called a ridge-dodger top ring.....
but with the price of decent rings, pistons and liner feel quite cheap.....
for around £300-350 u can get a full engine rebuild kit......
new liners come with new pistons and no machining is ness....they are made to the correct size.....
let me say if u want to fit new liners they dont come out easy.....
u will see on some sites that a big threaded rod and shaped washer will pull them out easy......bol***k's.....
I've had to use a 25 ton press to get em out.....in fact I only ever use the press now......
so if u dont need to replace the liners, leave well alone.....
one small thing, the block with the liners removed will need a deglaze.....
lastley I've had liners so stuck in the bores that they had to come out in bits.....
broke them up with a shaped cold chisel.....
my press was made almost just for this job....I can fit a 4 cylinder block on the bed.....

sorry dont know how to turn the photo....

 

[frank horton]

as for the center pop marks.....there's only 2 on the edge of the piston to worry about
BUT if the engine has run before with these marks forget em.....

 

[m_c]

That's something gone through the engine that shouldn't have.

I was more concerned about the marks on the cylinder wall of the first cylinder.

 

[Cobbler]

I don’t know if it still is, but it used to be accepted practice when re-ringing if the wear was in tolerance, press wet liners out, turn them 120 degrees reseal & refit. This would provide another thrust face, this could be done twice.

 

[Welderpaul]

This engine has run with these liners and these pistons. The piston rings are new.

I used the proper whatsname tool to take off the lip at the top of the liners - the liners are perfectly smooth, no marks and no lip at the top.

It's never going to get used to the degree it did before she retired, but will get used for road runs and rallies. I want it to be right, but if it's totally unnecessary work then i'm not going to do it. I really don't want any problems once its been rebuilt.

 

[nickk]

I second the comment re extraction,when I replaced my p3 liners,I had to use a small chisel to help extract them,the threaded rod technique only partially worked.
Is it a p3,or a ford engine?

 

[stormin]

That diagonal measurement on cylinder number 1 seems way over, are you sure it's correct? What are you using to measure the bores, snap gauges or a dial bore gauge.
Whilst it's that far apart I would put liners and pistons in. Not that much money for what they are and will see you out. Be a shame to out it back together and have blowby or oil burning and regret it.

Run a light bead of weld down the liners helps shrink and remove them.

 

[KimB]

What did you measure them with?

 

[Welderpaul]

What did you measure them with?

My new tape, its spot on. Do you think I need something more accurate @KimB

 

[8ob]

I am with the others on this, the piston/liner kits are so cheap its not worth messing about with old pistons etc. I use Powerall for Perkins rebuild kits, its all made in the same factory as the OEM stuff.

Bob

This kit is for a Perkins Phaser.

 

[KimB]

I found your measuring wheel to check the crank @Welderpaul

 

[Barking Mat]

What was the issue low compression? Smoking?

More than 60% of an engine is the cylinder head.

Though I can't comment on tolerances, did it run alright?

 

[Welderpaul]

I found your measuring wheel to check the crank @Welderpaul
View attachment 270973

Sorted

 

[Welderpaul]

What was the issue low compression? Smoking?

More than 60% of an engine is the cylinder head.

Though I can't comment on tolerances, did it run alright?

The block was (frost) cracked and a couple of the rings were broken. There was a 1/2" socket in the sump so it was worth opening up when i got it. It ran ok when i drove it, it was a lot time ago when I did, and i don't remember any problems.

 

[Bornfree]

I would just remove the ridge deglaze the bore and rebuild it.

 

[Barking Mat]

The block was (frost) cracked and a couple of the rings were broken. There was a 1/2" socket in the sump so it was worth opening up when i got it. It ran ok when i drove it, it was a lot time ago when I did, and i don't remember any problems.

Urrgghh!

Frost cracked block? How have you dealt with that?

Random socket in sump! Arrggh!

As above comment if it ran alright I'd put it back together.

 

[Welderpaul]

Urrgghh!

Frost cracked block? How have you dealt with that?

Random socket in sump! Arrggh!

As above comment if it ran alright I'd put it back together.

I tig brazed it.