Can anyone advise how oil gets to the top-end of the engine? As there are no oil feed holes through the barrels/head I’m assuming that it travels down the pushrod tubes, gets ‘distributed’ through the movement of the rockers and then drains back to the sump through the tube in the bottom of the rocker cover. I’m not sure how efficient that would be at getting oil to the inlet rocker and valve for instance, being at the top of the engine.
It must work however – I’ve just rebuilt the top-end and there was certainly evidence of lubrication.
After rebuilding the top-end has anyone experienced leaks from the pushrod-tubes? Not at the crankcase end where they are sealed with the rubber donuts – more where they are pressed in to the cylinder head.
I’m seeing evidence of some oil misting in that area; it’s either coming from the pushrod tubes/head or possibly travelling down the cylinder studs past the cylinder head nuts/washers. It’s a bit frustrating as everywhere else is oil-tight and these are the only places that I can think the oil can be coming from; this of course means having to take the motor out again, etc.
Any guidance or advice would be appreciated!
John
How's your knowledge on oil feeds (and top-end leaks)
Re: How's your knowledge on oil feeds (and top-end leaks)
Having looked at the parts book and the exploded diagrams relating to the cylinders, valve gear and oil pump. I have come to the same conclusion you have:- that the oil must somehow come up the push rod tubes, coat the valve gear and then drain back to the sump via the oil drain tube on each cylinder.
Now I know why the valve gear on these engines is mentioned in various place as "weak"! The engine design obviously is not meant to rev more than 4800 for the reason the lubrication of the valve gear can't cope.
As you say, it obviously works within the constraints placed on the engine and why there is a governor to limit engine speed.
I have not had to dismantle my engine yet, but I dare say I will have the pleasure before long so I am interested in the possible pit falls - one of which you seemed to have stumble upon. Did you take the push rod tubes out of your cylinder heads when you were doing your top end rebuild?
If yes, then I would hazard a guess that your problem lies there. I can't see very much oil getting passed all FOUR cylinder head nuts / washers without it showing up as more from one side than the other. Would it not be possible to take the bottom engine tinware off, clean the area around the push rod tube with a degreasing agent. Then run the engine and have another look to see where the oil is starting out from?
If no, then the same technique would still tell you if the leak was from the push rod to head joints or further out and therefore from the cylinder head bolts.
Good luck tracking the leak(s) down. How about some photos of your Haflinger? If yo need a guide on how to post them, I did one and it is under the "random photos" section.
John
Now I know why the valve gear on these engines is mentioned in various place as "weak"! The engine design obviously is not meant to rev more than 4800 for the reason the lubrication of the valve gear can't cope.
As you say, it obviously works within the constraints placed on the engine and why there is a governor to limit engine speed.
I have not had to dismantle my engine yet, but I dare say I will have the pleasure before long so I am interested in the possible pit falls - one of which you seemed to have stumble upon. Did you take the push rod tubes out of your cylinder heads when you were doing your top end rebuild?
If yes, then I would hazard a guess that your problem lies there. I can't see very much oil getting passed all FOUR cylinder head nuts / washers without it showing up as more from one side than the other. Would it not be possible to take the bottom engine tinware off, clean the area around the push rod tube with a degreasing agent. Then run the engine and have another look to see where the oil is starting out from?
If no, then the same technique would still tell you if the leak was from the push rod to head joints or further out and therefore from the cylinder head bolts.
Good luck tracking the leak(s) down. How about some photos of your Haflinger? If yo need a guide on how to post them, I did one and it is under the "random photos" section.
John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !
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Re: How's your knowledge on oil feeds (and top-end leaks)
Hi John – thanks for your reply. When I stripped the top-end down I didn’t remove the pushrod tubes, they didn’t want to move and there wasn’t a good reason to disturb them; it looks like they are a press fit in to the head.
I had thought about your idea of removing tinware and degreasing and trying to see where the oil is coming from but to remove all the tinware I would need to remove the oil return tubes and access/vision is pretty limited there anyway; also the fan tends to blow and distribute the oil across and through the fins making the source difficult to see. It’s damn near as quick to remove the engine for a more detailed look on the bench.
To update – I removed the engine last night and took off the cylinder heads. There was evidence of oil travelling through the bottom holes in the cylinder head. I know these were thoroughly degreased when I stripped the heads so the oil must be getting around the nuts/washers holding down the heads. There was quite a lot of oil, enough for it to drip out when I inverted the head.
It doesn’t look as though there is any coming down the pushrod tubes – however I’m going to degrease them at the top and apply some bearing adhesive, in the hope that if there is any gap that it capillaries down between the tube and the head.
I’m going to rebuild the top-end this weekend, using thread sealer on the studs and gasket seal around the nuts/washers and reinstall the engine this weekend – I’ll post with an update on the fix.
(PS I did post some (not very good quality) photos in this thread here http://www.thehaflinger.com/viewtopic.php?f=13&t=661 - I do need to take some more though, particularly of it in use)
John
I had thought about your idea of removing tinware and degreasing and trying to see where the oil is coming from but to remove all the tinware I would need to remove the oil return tubes and access/vision is pretty limited there anyway; also the fan tends to blow and distribute the oil across and through the fins making the source difficult to see. It’s damn near as quick to remove the engine for a more detailed look on the bench.
To update – I removed the engine last night and took off the cylinder heads. There was evidence of oil travelling through the bottom holes in the cylinder head. I know these were thoroughly degreased when I stripped the heads so the oil must be getting around the nuts/washers holding down the heads. There was quite a lot of oil, enough for it to drip out when I inverted the head.
It doesn’t look as though there is any coming down the pushrod tubes – however I’m going to degrease them at the top and apply some bearing adhesive, in the hope that if there is any gap that it capillaries down between the tube and the head.
I’m going to rebuild the top-end this weekend, using thread sealer on the studs and gasket seal around the nuts/washers and reinstall the engine this weekend – I’ll post with an update on the fix.
(PS I did post some (not very good quality) photos in this thread here http://www.thehaflinger.com/viewtopic.php?f=13&t=661 - I do need to take some more though, particularly of it in use)
John
Re: How's your knowledge on oil feeds (and top-end leaks)
Unless you have a good reason to want to use thread lock on the studs, I would advise against using it on the cylinder head end of the studs. It will make it far more likely that the next time you strip the cylinder heads that he studs will unwind from the crankcase rather than just undoing the nuts.
Far better to either use shake proof washers, or Nylock nuts.
As for sealing the studs to cylinder head holes, these washers (of the correct size) (http://www.ebay.co.uk/itm/Assortment-Bo ... 2a23211ddf) are very good at doing that.
Or you can do a minor mod to your cyinderheads. Counter sink the holes enough to be able to put an "O" ring on the stud(s) and then a shaker proof washer. When you do the nut up it will compress the "O" rings and do the same job as the Dowty-Washer!
John
Far better to either use shake proof washers, or Nylock nuts.
As for sealing the studs to cylinder head holes, these washers (of the correct size) (http://www.ebay.co.uk/itm/Assortment-Bo ... 2a23211ddf) are very good at doing that.
Or you can do a minor mod to your cyinderheads. Counter sink the holes enough to be able to put an "O" ring on the stud(s) and then a shaker proof washer. When you do the nut up it will compress the "O" rings and do the same job as the Dowty-Washer!
John
Haflinger 703AP LWB 1973 - (Once owned by Lady Sutherland & Sons.) Now called "Lurch" !
Have you hit the "DONATE" button at the bottom of the page after reading this post? Many thanks if you have!!
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Re: How's your knowledge on oil feeds (and top-end leaks)
Well that's the motor oil-tight now!
Good tips John, but I used what I had at hand - some Hylomar gasket seal under the standard thick washers, and ARP thread sealer (not a locking agent) on the threads/studs, and it appears to have been a success.
That's me finished work on the engine (for now anyway)..
Barrels honed, oversize rings gapped and fitted
Valves ground-in
Governor and butterflys in manifold removed and an electronic limiter fitted.
Oh, and I changed all the oils in the hubs/gearbox/diffs for Castrol Syntrax 75/90 - it's a good quality oil and doesn't have the same gloopy viscosity as the mineral oil does when the temperature drops - less drag, more power.
It seems to be running well, pulling stronger than it did before with very little evidence of smoking; I'm looking forward to the rings being fully bedded-in and getting a compression test done (it was about 80psi on each cylinder).
Good tips John, but I used what I had at hand - some Hylomar gasket seal under the standard thick washers, and ARP thread sealer (not a locking agent) on the threads/studs, and it appears to have been a success.
That's me finished work on the engine (for now anyway)..
Barrels honed, oversize rings gapped and fitted
Valves ground-in
Governor and butterflys in manifold removed and an electronic limiter fitted.
Oh, and I changed all the oils in the hubs/gearbox/diffs for Castrol Syntrax 75/90 - it's a good quality oil and doesn't have the same gloopy viscosity as the mineral oil does when the temperature drops - less drag, more power.
It seems to be running well, pulling stronger than it did before with very little evidence of smoking; I'm looking forward to the rings being fully bedded-in and getting a compression test done (it was about 80psi on each cylinder).