DJ2.1 Rebuild

[maxstu]

Many, many thanks. Recalling my ECU failed last year. It was flooding the bores with fuel.
Will check sidewall and the other pstons tomorrow and report back.
£170 per DJ piston at Brickwerks!

[Smiffo]

Many, many thanks. Recalling my ECU failed last year. It was flooding the bores with fuel.
Will check sidewall and the other pstons tomorrow and report back.
£170 per DJ piston at Brickwerks!

Do you know what is meant by "matching set" in this thread?

Were there different variants, or sizes? 
And if you buy 4 from a supplier, do they "match" them for you?

[maxstu]

Many, many thanks. Recalling my ECU failed last year. It was flooding the bores with fuel.
Will check sidewall and the other pstons tomorrow and report back.
£170 per DJ piston at Brickwerks!

Do you know what is meant by "matching set" in this thread?

Were there different variants, or sizes? 
And if you buy 4 from a supplier, do they "match" them for you?

Matching in weight. Even new they vary a little. If you buy used pistons they should be of a similar weight. By about +/- 10 grams, l think? Will have to look in manual tomorrow.

[Stesaw]

You said competent people Stu

As for the piston size, should be marked on the tops of the pistons

[ajsimmo]

Yes, weight matched. The tolerance is a whopping 10g, but that's cumulative reciprocating mass, ie piston & rod combo. I weigh everything and write it on the part, then combine them for the best balance. It's particularly important in opposing assemblies.
I aim for +/-1g.

Sent from my moto g(30) using Tapatalk

[maxstu]

Okay and thanks. Have ordered some digital scales. What is weighed together? Piston, rod, pin and sleeve?

While crank, cam, rods and cases at TEC, over the weekend, l met with an old friend of mine who is an old-school trained pattern maker. He now specialises in Rolls Royce and passenger airliner fabrications. With him came a set of micrometers and a very expensive tri-legged internal bore reader (to .005mm) in a fancy case.


Jon measured and re-measured all four pistons and four sleeves at the correct points. And came to this conclusion:



Conundrum time.

Cylinders 1 & 2 sporting an AMC head. VW head for cylinders 3 & 4. Yet sleeves 3 & 4 are still showing honing marks?

Sleeve 3


Sleeve 4


Pistons 2, 3 and 4 are VW Mahle. Piston 1 is identified by the following photos.





This piston also had a jammed oil ring.

What's happening here? Have l got an engine with 1st oversize (by honing) sleeves on 2, 3 & 4? And should l consider renewing piston and sleeve for No1. Clearance wear for cylinder to piston is 0.2mm. So is 0.146mm worth keeping?

[Smiffo]

I'm wondering if maybe we are overthinking it.

I'm assuming this is the engine that ran fine before in your van, and the only indication of an issue was the overheating after a water pump fail?

If so, would it make it easier to put the pistons / sleeves etc back in the position they were - assuming no damage found due to overheating - and work on the theory that if acceptable before, that it should be after too?

Feel free to shoot me down!! 

[maxstu]

Rat-tat-tat-tat!

If lve got the engine open, then let's give it the best love and care possible.

Also from Jan 2019 (about 13K back) l did a compression test.

No1 came back the weakest then. But still in spec.
No 1 147
No 2 151
No 3 155
No 4 153.

That old theory about the cylinder furthest from waterpump run's the hotest?

[Smiffo]

I'm hit, I'm hit!!! 

[maxstu]

Ha! Not too dissimilar to an emergency landing we had in a light aircraft flying from IOM to Liverpool John Lennon airport.

[Stesaw]

If it had a jammed oil ring then it probably wasn't doing a very good job, maybe the overheat stuck it in there?
I mean it's still in spec but I suppose it depends on what you want to do. Maybe source a piston and sleeve that's to spec with the others perhaps? or just replace the lot.. with a punch to the wallet

[maxstu]

If it had a jammed oil ring then it probably wasn't doing a very good job, maybe the overheat stuck it in there?
I mean it's still in spec but I suppose it depends on what you want to do. Maybe source a piston and sleeve that's to spec with the others perhaps? or just replace the lot.. with a punch to the wallet
[/quote

l think it had been jammed for some time. There is loads of carbon stuck around this piston and inside the ring gaps. A right mess.

Ive not got excessive money to throw at this engine. But intend, to the best of my abilities and with the forum's help, to make a decent long-term rebuilt DJ 2.1.

This article will become more readable once all this silly messing around is behind me and l can begin with actually putting parts together.

As expected with an engine rebuild, it is cleaning and measuring. Then more cleaning and measuring.

I may well take the sleeves and pistons to TEC for their view.

Meanwhile, l have an injector query to muse over. Starting a new thread tonight.

[maxstu]

If it had a jammed oil ring then it probably wasn't doing a very good job, maybe the overheat stuck it in there?
I mean it's still in spec but I suppose it depends on what you want to do. Maybe source a piston and sleeve that's to spec with the others perhaps? or just replace the lot.. with a punch to the wallet

I think it had been jammed for some time. There is loads of carbon stuck around this piston and inside the ring gaps. A right mess.

Ive not got excessive money to throw at this engine. But intend, to the best of my abilities and with the forum's help, to make a decent long-term rebuilt DJ 2.1.

This article will become more readable once all this silly messing around is behind me and l can begin with actually putting parts together.

As expected with an engine rebuild, it is cleaning and measuring. Then more cleaning and measuring.

I may well take the sleeves and pistons to TEC for their view.

Meanwhile, l have an injector query to muse over. Starting a new thread tonight.

[maxstu]

Hello hello! An echo.

[Stesaw]

I was gonna say
Yeah I was lucky and andrew had two pistons that measured the same as the ones that were decent on my engine