Afternoon all, I'm still new to all of this but getting there bit by bit. I've started running routine maintenance on the van as part of my goal to doing more work on the van myself. So last weekend I did valve adjustments, compression test etc. Anyway all cylinders reported a decent pressure (around 120 psi) bar cylinder one which was down towards 100 psi. I took the van over to my local air cooled garage (Kombi Klassics) and they confirmed this. My question is what would be the best course of action: Get the engine out myself and get the cylinders over to Kombi for them to inspect and then repair or replace as necessary (having never done this before its a little daunting but I'm up for it, and can't really justify/afford getting Kombi to do this at the minute). Get the engine rebuilt completely. I'd like to avoid this if possible as it isn't exactly cheap! Perhaps I could look at getting this done in a few years time if I go for the above option (or is this false economy?) I'm heading towards option 1 as the engine didn't have any loss of power or odd noises so hopefully there isn't a huge amount to be done. On a related note, is there anyone in the Poole area that has a garage large enough for my van for a little while? If I go for option 1 there's no way I'm taking the engine out on our gravelled driveway! (the number of odd little screws I've lost to this).
If that is the only reason (100 psi on 1 cylinder) I would not touch it. That is still quite reasonable. Put a tiny bit of oil down the plug hole on that cylinder and do the test on that cylinder again. If it makes no difference it may be a slightly worn valve rather than the rings etc. If it goes up the rings may be slightly worn but not enough for a rebuild.
Cheers guys. I did the old oil down the plug hole and retest at the weekend and it didn't affect the compression, I thought that meant the valves might be slightly worn so nice to see that ties up with your thoughts. So would the best thing to do be to carry on checking it every 3 months or so and if any of the other cylinders start to deteriorate only then think about doing further work? I've been using the trusty 'keeping your Vdub alive' book for most of my work which has been brilliant but still can't beat speaking to people either in person or on here.
Keep checking the valve clearances every 3000 as recommended, If one tightens a lot it really needs an eye kept on. If not just Carry on as you are. Regular maintenance
So being one for trying to keep on top of things I think what I'm going to do is get the cylinder heads off and take a look later this month. I've never taken the engine out before so this seems like a good excuse to take a look and the tinware could use a lick of paint (also will let me check that all tinware is in good nick etc). Have been reading the manuals for weeks so hopefully feel ready to give it a go. Hopefully its just a burnt valve which can be sorted.
Ok so I finely got round to doing this. Took the heads off and down to my mechanic in Wareham for a valve job. He resat and lapped them for me but said he didn't think they were the cause of the low compression on cylinder 1. I've taken the cylinder off and checked both the piston and cylinder for wear but it all seems fine. The recommended tolerances for piston rings look to be OK so I'm confused as to what it might be? Any pointers (go easy!). What would my best option be, to refit everything and get it running again to do another comp test or replace the cylinders and pistons now (I don't know a huge amount about the vans history so not sure how old they are). I'm hesitant to replace them all if it would run OK as it is for another year or so (cash is limited atm).
Maybe the head just needed re-torquing. Were there any signs of it blowing at the cylinder/head joint?
It seemed quite oily around the head so that's possible. I'm thinking I'll give it all a good cleanup, refit it as is and do a comp test to see what's going on on that cylinder now. I can always take it apart again in a few months if there is still a problem on that cylinder. Does that sound reasonable? Sorry to ask so many questions, this is my first time!
Sounds like a plan. You could go mad and fit new rings/hone the barrels while you're at it... ...and while you have the barrels off, remove the pistons and replace the big end shells - about a tenner and an extra hour. Then you've done your top end once and for all.
That sounds good. Think what I'll do is refit and then when funds are a bit more flexible look at rebuilding the top end completely myself. As long as I keep a close eye on the engine I think that should be fine.
Your readings are typical TBH. Borderline shall I/shan't I. If they were like that but all below 100psi, that would perhaps steer you to do "stuff". If whatever is the cause of the lost compression gets worse, the tickover will get correspondingly lumpier. The closer each barrel's compression is, the smoother it'll run.
So the engines back in! Can't quite believe I managed it but she fired up straight away. Need a little help on setting the timing though. I bought a timing light (powerspark) and wired it up but didnt get what I expected. Engine code is AD so I believe it's 7.5 before tdc. However timing mark appeared to the right of tdc. Isn't this after tdc? Timing light is adjustable so I'd thought that setting it to 7.5 would have the mark near to the top. Any thoughts. I've left timing as is for the moment as the engine runs as it is.
You need to rotate the dizzy to set the timing... Loosen the clamp, and with the engine running and the timing light connected rotate the dizzy clockwise or anti to align the timing!!
Yeap got the book out and see all that. Just seemed odd that the timing was after tdc as it is? Turning dizzy increased rpm so guess I need to adjust dizzy then set idle again?
