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Re: WBX-Unknown

Posted: 05 Jul 2018, 17:04
by 937carrera
itchyfeet wrote:I didn't know that.

:? Is that your way of saying you did ? :?


itchyfeet wrote: Did you know pistons have steel in them?

Depends what engine they are out of, the last set I bought had no steel in them, they were aluminium :)

Re: WBX-Unknown

Posted: 05 Jul 2018, 17:27
by itchyfeet
937carrera wrote:
Depends what engine they are out of, the last set I bought had no steel in them, they were aluminium :)

did you cut them in half to see?

Image

Re: WBX-Unknown

Posted: 05 Jul 2018, 17:35
by 937carrera
Nah, compression test result would have been lousy, looks like that piston needs new rings too

Re: WBX-Unknown

Posted: 05 Jul 2018, 18:01
by itchyfeet
I'm guessing that steel bar above the gudgeon pin is a reinforcement?
deffo steel I tested it with a magnet
DG/DF piston

Re: WBX-Unknown

Posted: 05 Jul 2018, 18:49
by 937carrera
Maybe I wasn't being clear enough, the pistons I am referring to were for another completely different engine, different manufacturer, not another WBX. This is the first time I have worked on a WBX motor. Learning along the way

Re: WBX-Unknown

Posted: 06 Jul 2018, 11:14
by 937carrera
I made a decision today. I decided to take the con rods to the engineering workshop for measuring.

It's going to cost me some cash, but it will provide a definitive answer on the condition of the con rods, helps with my learning whatever the answer.

I could have sent them to you Bob (thanks for the earlier offer, I had not forgotten) but as your van is passing its MOT on Monday in advance of your trip to Yorkshire I figured it was easier /quicker just to take them to my usual place. Rods are quite heavy so postage would have been quite a bit too, thanks anyway much appreciated. They are only 15 minutes down the road too.

I already got a suggestion of what may have caused the uneven wear...... keeping you in suspense until next week when they've done the work. :D

Time for some more component cleaning I think.

Re: WBX-Unknown

Posted: 06 Jul 2018, 13:07
by 937carrera
Piston number 1 has had a second clean today, not ready yet, but decently clean.

I'm curious about some of the markings. The arrow and piston size I understand. I looked in Bentley and did a search and I couldn't see what the letter D to the left of the piston size represents. What I thought was a piston honing group (I II or III is what I expected to see) is actually two sets of numbers 530 on top, 1196 below and three linking lines. Number 3 has the same marks

Any idea what they are ?, I could see the 530 perhaps being piston weight :?:

Looks like a foreign object has made contact with the piston too at some time. I'll just file that down to eliminate a potential hot spot in the squish area, don't want unneccesary potential for pre ignition.

Image

Re: WBX-Unknown

Posted: 06 Jul 2018, 18:13
by 937carrera
Answering my own question

I found a Powerpoint presentation https://player.slideplayer.com/12/3440782/# which had the answer. Quite an interesting presentation too. Available as a video with additional synthesized commentary https://slideplayer.com/slide/3440782/#

Apparently the three bars are actually the M for Mahle in their typeface, the numbers are production numbers.

The top row indicates what plant the piston was made in.

The bottom row indicated when the piston was made, so these oversize pistons were made in November of 1996

I still don't know what the D is though

Re: WBX-Unknown

Posted: 06 Jul 2018, 20:18
by bigbadbob76
Aye, better to take em 15 mins down the road than send em half the length of the country and back, good plan mate. :ok
I was thinkng 1196 would either be nov '96 or 11th week of '96.
Dunno about the D though. :?

Re: WBX-Unknown

Posted: 11 Jul 2018, 14:17
by 937carrera
I spoke to the engineering workshop today. They haven't looked at the rods yet, will need to make up a mandrell to do the measurement and asked me if I was going to reuse the bearings (if I was they would have marked them, left them in to get the benefit of their experience. I thought the last comment was quite interesting.

So with nothing happening on the rods I turned my hands to cleaning the pistons. I used diesel, brakecleaner, brass bristle brush, green scotchbrite and dry brillo pads as I didn't have any wire wool ready to hand.

Yep, I know there's only 3 in the picture, number 4 is soaking as I type this

Image

That then led me onto thinking about the gudgeon pins. I went on an internet search, then searched on here to see what the dimensions and wear limits were, eventually ending up on the WBX Log page. Along the way there was a post that said the gudgeon pin was 24mm, though I suspect that is a nominal 24mm http://forum.club8090.co.uk/viewtopic.p ... &p=8158242

Like Paul I couldn't find a WBX spec so widened my search, first looking at a/c CU engine then going back to original type 4. My Haynes manual for the 412, is vintage 1974, so it has lots of information in it and actually states the gudgeon pin clearance is 0.01mm to 0.04mm. In case friends across the water are looking I'm also going to say wrist pin, but you can do the conversion to thou yourself :D

Next I measured my gudgeon pins. As you can see in the pic mine measured 23.985mm - I did carefully calibrate the mic before measuring. The pin measures the same at the ends where it sits in the piston, so doesn't appear to be worn. (small end constantly rotating, gudgeon pin not, when in use) I zoomed in on itchyfeets pictures and his pin measured 24.005mm with the small end measuring 24.02mm giving a clearance of 0.015mm. Pretty good :)

I don't have my rods so cannot measure my little ends and get the clearance. From feel before removing the pistons & withdrawing pins I would say that the little end fit was good.

You should also be able to see that I have carefully filed away the little burr that was on the top of of piston 1 so that won't be a hot spot in the future

Image

Re: WBX-Unknown

Posted: 13 Jul 2018, 15:24
by 937carrera
This afternoon I collected my con rods from the engineer. They are absolutely straight, not even one thou out. :ok

So that's good news and field engineering was not the right approach in this case. When it comes to measuring rods, as they say, don't do this at home kids :D

I also took piston number 3 and gudgeon pin to check for play. He examined them, slid the rod on and after the expected head tilting as he felt the play at the pin end and the centre said there's nothing wrong with them and it'll be even better when there's a film of oil on.

The additional side play at the little end was a result of the wear in the bearing shell. Initial thought was that it was perhaps caused by the little end sticking on the pin and exerting some side pressure, following the examination this afternoon there isn't anything to be concerned about.

I'm going to double check that the crank journal is round, measuring at more points around the journal and across it. I'll also inspect the bore again, I couldn't see any damage at first glance but maybe a broken ring will make a small change the side loading on the piston from the rings which transfers through to the bearing. Dunno :?:

I've been told to get some new shells and re-assemble. :!:

Re: WBX-Unknown

Posted: 13 Jul 2018, 16:42
by itchyfeet
Good news.
May we ask the cost of checking the rods?

Re: WBX-Unknown

Posted: 13 Jul 2018, 16:45
by 937carrera
£30, which included the tooling

Re: WBX-Unknown

Posted: 13 Jul 2018, 17:26
by itchyfeet
937carrera wrote:£30, which included the tooling

Can't get anything done for 30 quid down here.

Re: WBX-Unknown

Posted: 13 Jul 2018, 17:57
by 937carrera
:rofl I know, thirty of our finest hard won northern pounds too, without wanting to become a character in an Adil Ray sketch... "they know me"

You did set that one up, I just headed into the back of the net :rollin

...and the guy has 60 years experience too