Rebuild Thread (Probably)

[937carrera]

I think it's just a typo on the BW listing then, and you'll get a 375.

Looks like you have a response from 300CE to your wanted ad already

[Ciaraneng]

I have a second hand late DG head that’s yours for the price of postage if it helps Ciaraneng - one of the exhaust studs has snapped so will require a recoil and a valve is missing (you’d probably want to change them anyway) but other than that all looks ok. I bought it as a spare for when I did my rebuild but didn’t need it.

Let me know and I’ll fire over some pics.

That's very generous of you 300CE and might be a great option. It may be best to see what arrives from BW and try to match that.Or not maybe. I'm a bit confused TBH.

[300CE]

No worries mate - Happy to keep hold of it for a couple of weeks before sticking it on eBay so just let us know.

[Ciaraneng]

No worries mate - Happy to keep hold of it for a couple of weeks before sticking it on eBay so just let us know.

That would be great. If the it turns out that I can use an early on one side and a late on the other, it might be a good option. If not, it might still be a good option to match with one of the existing.

Thanks again, much appreciated.

[937carrera]

I think it's just a typo on the BW listing then, and you'll get a 375.

I've been mulling this over, in the context of Andrews comment about searching on Classic Parts using the 355 number and BW also using that same number. My copy of ETKA doesn't list the part number for bare cylinder heads for the DG engines, only the DF.

DF heads are 355, suffix B
Late DG are 375 suffix C
we've seen early heads with the 375 part number, no suffix
So the very first early heads were probably 355 part number, no suffix, with suffix B for the DF

Quite happy for anyone to educate me further

[Ciaraneng]

This just in from Michael in BW to help clarify what's going on with the cylinder head P/N's:

(the) Part number is 025101355
The number on the casting [i.e. 025101375] is VW's internal number for the bare casting and would never have been available from that part number.
It's then assembled with the other parts… studs, guides etc. and becomes 025101355

So it looks as if I will be getting an early cylinder head from BW. The question is whether I should be using an early or a late head. My chassis no. and log book indicates that van itself is a 1983 and it seems to have an early WBX crankcase based on this post.

My engine No. is DG024955. Does anyone know if there is a way to find out based on the engine number what year it is and what heads should go with it? Should early heads and early crankcases always go together?

[itchyfeet]

early case/engine has only one oil presure switch between push rod tubes not one by water pump

[itchyfeet]

this is right 99%
early late case by Paul_Barr, on Flickr

[Ciaraneng]

early case/engine has only one oil presure switch between push rod tubes not one by water pump

Thanks Paul. Yes, only one pressure switch and it's between the push rod tubes so it's an early case. I'm wondering was it a mistake on the part of a previous owner to put late heads on it? If so, a bigger issue for me might be locating a second early head so that I can balance the compression on the two sides. Or maybe mixing an early and a late will be fine? Maybe I'll do silverbullet's cc check when I get my early head from BW and see how the early compares to the late from a volume perspective. I guess I should check the pistons too in case they were changed at the same time as the heads - assuming again that the heads were changed.

[937carrera]

this is right 99%

I am some of that 1%

Use the info from Paul to identify your case as being early / late. AFAIK there's no issue using early / late heads on early / late cases, though it's safe to assume that the late heads were marginally improved, probably something related to with gas flow on the exhaust side which may have been done for reliability rather than performance. Anyway, as I said AFAIK, others will have greater experience.

Thanks for posting the info from BW, that nicely closes off the question.

[937carrera]

Thanks Paul. Yes, only one pressure switch and it's between the push rod tubes so it's an early case. I'm wondering was it a mistake on the part of a previous owner to put late heads on it? If so, a bigger issue for me might be locating a second early head so that I can balance the compression on the two sides. Or maybe mixing an early and a late will be fine? Maybe I'll do silverbullet's cc check when I get my early head from BW and see how the early compares to the late from a volume perspective. I guess I should check the pistons too in case they were changed at the same time as the heads - assuming again that the heads were changed.

Please do carry out the cc checks. I did get round to ordering some perspex last night, but it would be good to get some other decent comparative measurements, especially from someone with both head types.

[Ciaraneng]

I think I've decided to go with two late heads so I'll be returning the early head to BW when I get my order. I'm afraid of imbalance between the sides. I've removed the pistons using the itchyfeet rawlbolt method (thanks Paul ). I had one broken ring when I removed the pistons. I've a dial gauge on order for end drift measurement. I've also rings, a ring compressor and remover as well as a coolant pump and a gasket set on order.

The big question now is whether to split the case and replace the bearings or to leave it. My oil pressure at 2000 rpm was just over 30 psi. I was thinking about just ordering a new oil pump and a puller and leaving the case sealed. What are the main advantages of splitting the case and what are the main things that can go wrong? How big a job is it? Any advice from those who have done it before

Another question is whether to hone the barrels or leave them? To the unskilled hand, are you better to leave them and hope to get an improved seal from new rings or risk scratching them by honing?

Thanks in advance.

[itchyfeet]

splitting the case is easier than the top end
reason is to change cam bearings which are often shot and cam which is often worn
main bearings are usually good but big ends can be worn on high mile engines

30 psi is 2 bar so only just in spec assuming you tested at 80 deg C temp makes a big difference.
if you are this far I'd do it.

[937carrera]

I would agree, having gone this far, you might as well do the full rebuild, a few comments though:

Cam bearings - almost certainly need replacement, as Paul said
Main bearings - You'll probably have the early one piece thrust bearing, I would check availability of replacements before splitting ('cos I don't know yet), assume std size
Big end bearings - you can get a view on bearing wear by doing a measurement of side to side play on the con rod before splitting the case. Over ~1.1mm indicates there might be an issue
Big end bolts - They might be stretch bolts, in which case you must not re-use them. Stretch NLA, non stretch available from somewhere

In general, get your shopping list together, then check where you can source bits from

[itchyfeet]

Thanks again Carrera. Learning all the time here.

To add to the confusion, the BW (and VW) code listed on the BW page is 025-101-355 but one of the pics clearly shows a casting no. 025101375. I guess I'll wait and see what arrives...

What is going to arrive is an early VW DG head with 025101375 cast in as shown in the picture.