No.4 Inlet valve bucket oil starvation??????

[dougie1]

Hello everyone,
this oil starvation problem has me totally baffled so apologies for the long message but need to give the full story.
Had totally rebuilt my A4 motor and it fired up first start.
Run the motor in the garage about four times, approximately 20 minutes in total.
One of the cam end caps was leaking so removed the cam cover to sort.
On removal of the cover noticed No. 4 inlet valve bucket was dry and slight markings on the cam lobe. All other cam buckets were full of oil particularly the the exhaust side.
I removed the sump pan to find a load of paste type material in the oil.
The head had been thoroughly washed and air blasted after been vapour blasted but had not removed the head oil way end plugs so I removed the head and the end plugs and did find some blast media in the oil way at No. 4 inlet end.
Thought I had found and sorted the problem so thoroughly cleaned the oil ways and bought brand new standard cams and bearings.
Firstly I bolted the cams in the head without the valves in so to check the cams could turn freely, ie. oil can get between the cam and bearing.
I also stripped and checked the oil pump, fitted new gasket and checked it turned freely.
Also poured oil down the oil ways on the barrels and oil came out of the bottom of the engine on both sides, so no restrictions there.
I re-assembled the engine but left off the spark plugs, carbs, exhaust and cam cover.
Using the starter motor I turned the motor over until the oil light went out and checked for oil coming out between the cam and bearings.
Had to turn the motor on and off a few times to see a build up of oil, but the more I turned the motor the better the oil flow to the cam buckets. The exhaust cam buckets were saturated in oil and not as much on the inlet side BUT hardly any oil at No. 4 inlet bucket.
I am totally lost what to do next, appreciate any advice/ideas.
Regards, Stephen.

[warren3200gt]

Had a similar issue on mine except on no4 exhaust. Eventually tracked it down to a blocked with silicon cross drilling. Thanks Mr media blast man.
You say that you have checked yours but its the only restriction I can think of that would cause your symptoms even if only partially blocked.

[zed1015]

If the oil supply to number 4 inlet bucket is blocked then number 3 would also suffer the same issue as 4 get's it's oil first from the same source as 3 which is secondary overspill oiling from their respective cam shaft bearings.
The only way #4 inlet would solely be starved of oil is if the vertical drilling for #4 cam bearing was blocked directly under the shell but not the whole horizontal cross drilling which also feeds #3.
If this is not the case i would be looking at #4 cam journal/cam shell clearance as if this is too tight it will also prevent oil reaching the cam bucket and there will be evidence of starvation on #4 bearing shells too.

[dougie1]

Thank you for both comments particularly the second one as I thought the same but have measured the new cam shafts and were correct measurements, plus I fitted the cams without valves so I could check they spin/no tight spots.
Last night I removed the inlet camshaft and using a syringe I squirted oil down No.4 inlet oil way and oil shot up out of No. 3 inlet oil way. Totally baffled.
That’s why I am thinking can it be a restriction on the right hand oil way between the crankcase and the barrels oil way? Not sure so will have to take the barrels off.
Cheers, Stephen.

[zed1015]

If there was a restriction at the barrel base it would affect both 3 and 4 inlet equally and also 3 and 4 exhaust UNLESS #4 cam journal clearance was subtantially tighter than the rest in which case the oil will take the path of least resistance and favour the other journals until the oil pressure and volume over came the restriction on 4.

[kev edwards]

Had the very same problem the same bucket, no restrictions cams free, I have a cam with the lobes cut off so I could check with the head torqued down, it just would not oil up, so I took on info from someone else and put a 45 degree angle very shallow groove in the lower shells, this cured the shortage with no ill effects whilst quietening the top end down, maybe you are getting a slight twist when tightening head down, you may also have a non original cam cap as mine has
Warren on a side note I remember that silicone and thought that bloody cable tie we used to push the stuff out was going to get stuck.

[warren3200gt]

Yep, good spot, thanks and the airbox with no air inlet was a bit of a twist also. No wonder it wouldn't run for more than a few seconds before cutting out.

[z1bman]

you need to remove the oil gallery blanking plug & spin the engine over to check the oil flow to the inlet cam

[r3sc]

Reading through this is very interesting and I’m going to be facing a first start after total rebuild of the top end in the next few weeks.

I wondered if there was any way of pre priming the lubrication galleries and the oil feeds to the cams etc prior to even turning it over on the starter?

I have assembled the top end using a good quality engine assembly lubricant but I still have some concerns.

I assume that if I were to remove the oil gallery plug from the right hand side of the crankcase and then inject oil into it using a large industrial syringe, the oil would take the path of least resistance and short circuit back into the sump via the oil pump!?

If this is the case, any other ideas?

What do you think guys?

[zed1015]

I wondered if there was any way of pre priming the lubrication galleries and the oil feeds to the cams etc prior to even turning it over on the starter?
If this is the case, any other ideas?
What do you think guys?

I've been building these engines for 40 odd years and never needed to do anything other than lube the components as it goes back together.
Some of my builds don't even include the starter motor and are fired on the kicker so don't even get spun over prior to starting.
There's no need for any sort of elaborate pre start lubrication fiasco.
These motors are high volume oil flow and the oil gets round the engine very quickly.
If they have been lubed correctly on re-build there's no need to do anything else.
A pre lubed engine will be more or less in the same oiled state as one that was run last week or yesterday and you don't go faffing about with big syringes etc every time you start the bike otherwise do you ?

[kev edwards]

I wondered if there was any way of pre priming the lubrication galleries and the oil feeds to the cams etc prior to even turning it over on the starter?
If this is the case, any other ideas?
What do you think guys?

I've been building these engines for 40 odd years and never needed to do anything other than lube the components as it goes back together.
Some of my builds don't even include the starter motor and are fired on the kicker so don't even get spun over prior to starting.
There's no need for any sort of elaborate pre start lubrication fiasco.
These motors are high volume oil flow and the oil gets round the engine very quickly.
If they have been lubed correctly on re-build there's no need to do anything else.
A pre lubed engine will be more or less in the same oiled state as one that was run last week or yesterday and you don't go faffing about with big syringes etc every time you start the bike otherwise do you ?

Exactly how I was shown and have been doing all the time I've been playing with motors.

[r3sc]

Cheers guys. Guess I’ve been reading too many forums and not been paying heed to the correct engineering practices which I use anyway!

[dougie1]

After reading everyone’s comments on this forum plus the ones I received on the Butchered Classics Facebook site regarding oil starvation to No. 4 inlet cam lube, I removed the head, barrels, sump and oil pump. Everything was clean,ie. no sign of any aquablast media like the first strip.
I then carried out the following,
1) Made up a small hose from the air line and fitted into each oil-way in the head blasted air down each - No restrictions.
Note; the 1st strip I removed the head oil-way blanking plugs to check oil-ways were clear.
2) Checked the barrels oil-ways - No restrictions.
3) Removed the crank case oil passage tube screw plug - Could not see any restrictions.
4) Made an attached connected to the air-line that screwed into the oil-filter screw hole in the crank-case.
5) The long hose from the air-line to the oil-filter connection was loaded with engine oil and blasted it through the oil-filter route and oil blasted out of the oil-ways - No restrictions in the crank-case oil passage tube.
6) I replaced the crank-case oil passage screw plug and blasted oil again up the oil- filter route - Oil blasted out of the oil-ways either side of the crank-case oil passage tube.
7) I even checked the Oil Pressure Relief By-Pass valve.

All the above checks on top of checking the cam tolerances, checking the cams turn freely and the oil pump checks, I am definitely at that point of no idea what to do next to find the route cause,ie. very little oil getting to No. 4 inlet cam lobe.
Any more thoughts would be appreciated
Cheers, Stephen.

[kev edwards]

After reading everyone’s comments on this forum plus the ones I received on the Butchered Classics Facebook site regarding oil starvation to No. 4 inlet cam lube, I removed the head, barrels, sump and oil pump. Everything was clean,ie. no sign of any aquablast media like the first strip.
I then carried out the following,
1) Made up a small hose from the air line and fitted into each oil-way in the head blasted air down each - No restrictions.
Note; the 1st strip I removed the head oil-way blanking plugs to check oil-ways were clear.
2) Checked the barrels oil-ways - No restrictions.
3) Removed the crank case oil passage tube screw plug - Could not see any restrictions.
4) Made an attached connected to the air-line that screwed into the oil-filter screw hole in the crank-case.
5) The long hose from the air-line to the oil-filter connection was loaded with engine oil and blasted it through the oil-filter route and oil blasted out of the oil-ways - No restrictions in the crank-case oil passage tube.
6) I replaced the crank-case oil passage screw plug and blasted oil again up the oil- filter route - Oil blasted out of the oil-ways either side of the crank-case oil passage tube.
7) I even checked the Oil Pressure Relief By-Pass valve.

All the above checks on top of checking the cam tolerances, checking the cams turn freely and the oil pump checks, I am definitely at that point of no idea what to do next to find the route cause,ie. very little oil getting to No. 4 inlet cam lobe.
Any more thoughts would be appreciated
Cheers, Stephen.

Mine was exactly the same, could not find a reason for it so that's when i resorted to what i mentioned in a previous post.

[z1bman]

have you removed the rear blanking plug which is the horizontal drilling for the oil way. as shown on the left & right side of this photo i presume you have checked the small tapered o ring that that seals the oilway between the crank case halves.