White smoke - 300TDi

[Bowie69]

If you change the rings, you need to hone the corresponding cylinder. 

[Peaklander]

I’m not surprised to hear that 😃 Presumably they need properly bedding in with new surface preparation?

[western]

measurements look good, definitely hone all the bores if you fit new rings to all pistons. 

if the core plugs look good leave  them alone. 

mine are 24 years old,  I didn't replace them during my engine rebuild., using good quality antifreeze mix will keep them good.

[cackshifter]

I must admit I would put a set of big ends in simply because they are relatively cheap and you are in there - I'd also check the rocker shaft for wear, though that is something you can turn over and use the other side. The core plugs would have been changed by Turners; assuming they aren't leaking and you have kept the antifreeze up I would try to leave well alone, but do check them. If you have to change them, you prise them out (knock or drill a hole in the middle and prise from that) and then squarely knock in the new one with a smear of sealant around it (use a socket to spread the load). But it doesn't sound like  you'll have an issue with them. I'd check the no.2 oil jet. But yes as above, either change rings on a cylinder and hone that cylinder or do neither. And I would get some running in oil for the initial fill.

[smallfry]

Personally, I would do all the bores and buy a new set of AE or other quality rings for all.

Something not touched on when honing with the engine in situ which is not a problem when the engine is out and disassembled, is that it is VERY, VERY easy to hit the crankshaft or block webbing with the hone.

You can protect the journal, but you will almost definitely bugger up the honing tool. You MUST be aware of how far down you can go, so mark the shaft or make some sort of reference point.

When I have done this, I always buy a few tins of aerosol brake cleaner to flush away any swarf and stray carborundum, and then blow it all clear with an airline. Its worth a tenner or so IMO.

[monkie]

That's a very good point. Pack plenty of rags at the bottom of the bore over the crank. 

[Ex Member]

As far as the bearings go, you need to measure them with plastigauge.

[Peaklander]

Yes I have read-up on how to use that. A new set is £23.40 from Turners though, so not expensive. Presumably I could buy a set at std (same as on) and direct fit?

Edit:

Also I have cleaned-up all the pistons but on number 2 the ring to groove gaps are over spec. Not much but they are over on top and middle rings. I am assuming that the rings are too hard to wear and it must be the piston. It's half expected of course.

Edited January 21, 2020 by Peaklander

[Peaklander]

I'm moving back to my vehicle thread now as I know where I am and what I'm doing with the engine re-build.

The position is, that the white smoke (original reason for this thread) I hope has been cured with a couple of new nozzles and a full clean and check of the injectors. I checked the FIP timing with a dti and it is good.

The excessive oil in the intake system that caused me to pull the head has, I hope been caused by excessive blow-by on #2 cylinder. There I have lost the honing at the back of the bore and the rings were very sticky. On cleaning-up, the ring to piston gaps are over spec on top and middle. So I will replace that piston. Speaking with Frieda at Turners, she pointed out that #2 is right next to the turbo. I hadn't thought of that but she seems to think that is why.

I am getting the cylinders honed in a couple of days by a mobile company. I know, I know - I could do it myself but factoring in the cost of a tool, I'm not really paying too much and the job will be done by the weekend. I have told the guy that the turbo and manifold is off and I have already removed the oil jets which would get in the way.

I checked these oil jets and they are OK. the pipes blew through, although the oil was a bit thick but it was only 5C. The banjo bolt non-return valves seem ok with a little push of welding wire. Interestingly Frieda said that they don't refit these with the copper washers anymore. I queried this and she checked with their engine builder and it was confirmed. Strange but true. So I could buy some more (8 and 10mm I think) or not bother. The existing ones are a bit deformed and not worth annealing otherwise I'd do that.

The conrod bearings shells aren't warn at all and are at standard. Taking @cackshifter's advice, I will change these but can't see any reason to plastigauge for sizes as there is no visible wear. Frieda said the same.

So, this morning I have ordered one +20 piston set which has rings, gudgeon pin and circlips, three groups of +20 rings, a set of conrod bearings at standard and an oil filter. There's a couple of other gaskets and stuff from elsewhere but that is the main bill to pay today. The cost mounts up.

I'll probably head back over here next.

 

[lo-fi]

Forgive me if I've missed it, but did you check the ring gaps on number 2? 

[Peaklander]

Yes two posts above. The max on top ring is 0.232 and gap is wider. Actually it’s a visible difference. The second ring gap is also over. That’s why I’m going for a new piston. 

[lo-fi]

Ah, I mean the gap between the ends of the rings when installed. 

[Peaklander]

😀 I see. No, I just thought that I'd buy some new ones...maybe that is being a little extravagant but they will be here today.

I remembered that there was some advice about the rocker shaft or was it the rockers? I have read-up on where to measure wear in the shaft so I will do that too. Not sure how to assess wear on the pads and the valve caps are only 25K miles old.

[lo-fi]

The ring gap is far more important than the clearance in the groove. The damage on number 2 and your description are consistent with rings being fitted, not gapped correctly and lacking sufficient clearance. That clearance is vital when they heat and expand, or they deform, bind up, scuff the bore and damage the ring grooves, all of which can be seen on your cylinder 2. Some rings come "pre gapped", but not something I'd trust to luck. 

Shows the process nicely:

 

 

[Peaklander]

I’ll have a look at that, thanks. I am assuming that no one has been inside the engine since it was provided by Turners in 2003 and therefore I’ve faith that they were installed correctly.

Are you saying that there might be a bit of ring adjustment needed even though they are specified at +20 and the bore isn’t worn? Is that going to be because of the slight hone?  ( I will watch, promise but supposed to be doing tax return). 

[cackshifter]

The problem is that as @lo-fi says rings are fitted so that there is a small gap between the ends of the ring when they are cold. As they warm that gap shrinks. If they warm to the point where there is no gap, they can push against the bore walls causing a scuff, and I think he thinks that what you have had happen. What you should do is take the rings off the piston, push each ring into the bore  after honing as that will affect the size slightly, and measure the gap between the ends (with feelers). If the gap is too small, it is normal to file the end slightly (and very carefully) to make the gap big enough. In theory with pre-gapped rings the ends will be correctly gapped already, but just in case....

The rocker shafts wear on the underneath - it'll be fairly obvious I think if it has.  But... HMRC calls... I know the feeling

[lo-fi]

That's my working theory, yes. Turners have a great reputation, but even the best technician is not 100% infallible. 

Modern rings are usually pretty good, but it absolutely needs checking and adjusting. The ring manufacturer doesn't know exactly what the bore sizes are going to come out at or how much a hone will take off, so it's impossible to make a ring that's guaranteed to fit straight out of the box with the correct gap. Too short and blow by will be excessive; too long and they'll bind. Better to have a little extra which can be trimmed to get it spot on during the build, so out if the box they're usually on the tighter side of the spec. Worth remembering that a single thousandths change in diameter makes Pi times that change in circumference. 

Regardless of what has or hasn't gone on before, I hadn't seen ring gap mentioned in the thread, so thought best to bring up before you put the fresh ones in. 

 

[Peaklander]

I'm really glad you did as I breezed past that bit in the overhaul manual, just making that "I thought" mistake. My Dad used to say " you know what thought did, don't you?" I never did find out the answer to that one.

The manual says check with the rings half way down the bores. It's easy to push down with an inverted piston but getting them back up - is that with great care by hand, keeping them level or are they better to be turned and then squeezed by hand to pull up? It sounds a little tricky.

[lo-fi]

I've been caught out so many times that way myself... 

Just ease them up gently and evenly, they're quite robust as long as you're careful. Rotate and pinch works too, but put one end over the other to keep it all stable and ease the pressure and go easy. You'll soon get a feel for it.

If you don't have already, I highly recommend a set of ring pliers BTW

[Peaklander]

The mobile engine re-bore guy came today and honed the cylinders. It was great to see it done properly. I don't have a very good pic of the swirls now as they are coated with oil. The surface is slightly different but what's more notable is that I can hear a noise when I rub.

I cleaned the top of the block and all holes and the surfaces of the sump and bottom of the block. I'm hoping to check the ring gaps on Sunday and start re-assembly.

The honing tool is quite a beast and the motor is very heavy. After, the bores were given a good kerosene wash and then I cleaned-up the crank and emptied the drip trays which are stainless ones from an old food factory machine.

[Bowie69]

Proper job with that thing, reassuringly heavy and old school

[cackshifter]

Hi, sorry to preach, maybe to the converted, but it's vital to check the bores are perfectly clean. Wipe with a white kitchen towel, if it shows dirt, clean again. The hone will leave minute pieces of grit, which won't help your engine if left. It's common to scrub with detergent and water, but maybe that wouldn't suit the crank.

[western]

Great news from that one photo the bores look great. 

[Peaklander]

Thought that maybe I'd update this thread after all rather than my other one.

The honed bores now look like this, #1 to #4

 

I assembled the new piston for #2 to the conrod. It is supplied with a new pin and circlips and Turners supply KS ones, which I believe are the dogs dangles. Then I measured the top ring that was on #2, as when I looked closely I thought I could see a variation in thickness.

So I was right it is very worn. This variation must have been caused by the piston sticking I presume. The two measured points are within a quadrant.

A new ring measured:

 

I checked all ring gaps at the bore mid-point as per the manual and then assembled to the piston. Thanks @lo-fi for the suggestion to buy some ring pliers. What a difference. It is still a lengthy job and I took great care not to scratch the bores although there are a couple of marks but they must be insignificant as i brought the rings up very carefully. It's amazing what a difference the honing has made to the feel of the rings on the bore surfaces. You can hear the friction between them.

I checked the oil jets again. I had already fitted them but I wanted to blow back up the block from the point where the banjo bolt screws in, just in case there was anything in there. I don't know if this did any good and I then had a second dose of the fiddly task of re-fitting the jets with the crank in the way and no room for fingers.

Finally I replaced the big end bearing shells and found some tube to protect the cap bolts as recommended. They should really have been on at piston removal. 

I cleaned and cleaned the kerosene / honing powder mix off the bores, crank and block sides. The honing guy had given the whole thing a good sluicing with paraffin but as @cackshifter advised, there was a fair bit left to remove.

Next it's piston insert time.

 

[Bowie69]

Excellent, honing looks great!