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Posted: Fri Oct 02, 2009 4:25 pm
by Hedrock
JB17Atita wrote:If only I new man......
Can't seem to find it.....
I havne't been able to crack the case because of money and time shortage (no job and university occupied)
I now that there is now divine being that would tell me in my dreams wich is the exact cause, but if only I could now precisely what it is I would jump right on it.....
I was just giving it a LOTTA thinking and I wonder.... How can a different size of bearings (std for 0.10 for example) would affect on MY oil pressure disastrous drop? Too much gap? please enlighten me on that. Maybe that way I would get sufficient will to open the case and get to that.....
Is it really possible that the driven gear of the oil pump can get stuck, and the driving pin is just turning loose, when it's hot???
can I realy come up with the solution without diving into the case? or that's just a myth that I have created in my distrubed-by-this-trouble head??
Any answer, comment, critic, guidance will be very much appreciated
feel free to convinve me that I'm wrong (or right) I just need reasons.....
What's the (fill in the blank) reason for this? Still i say, help please
P.S: can it be the oil screen noto letting enough oil for the pick-up tube, at the drain plate? Nahhh.... (or can it?)
This actually happened to Leatherneck on his car. The drive gear in the oil pump was spinning on the shaft that goes to the cam gear and he had very little oil psi. We changed the pump and all is well.
Posted: Fri Oct 02, 2009 4:30 pm
by david58
Hedrock wrote:
This actually happened to Leatherneck on his car. The drive gear in the oil pump was spinning on the shaft that goes to the cam gear and he had very little oil psi. We changed the pump and all is well.
Hedrock explain why it was spinning is the gear keyed or pressed on?
Posted: Fri Oct 02, 2009 4:37 pm
by perrib
Did you start with the easy stuff, checking the oil plunger and oil pump gears to case clearance and see if the thin cover gasket was installed?
You could heat the drive gear in oil and see if the drive shaft slips. If you have standard bearing on a crankshaft cut .010" you now have .015" to .017" clearence. You now have 10 times more clearance than the limit. VW designed the engine to have correct oil pressure with .0015" to .002" clearance. It might not be linear but you now have 1`0 times less oil pressure.
Posted: Fri Oct 02, 2009 4:58 pm
by Hedrock
david58 wrote:Hedrock wrote:
This actually happened to Leatherneck on his car. The drive gear in the oil pump was spinning on the shaft that goes to the cam gear and he had very little oil psi. We changed the pump and all is well.
Hedrock explain why it was spinning is the gear keyed or pressed on?
It wasn't keyed. When David took the cover off and turned the engine over you could not tell. We only noticed it after he placed his thumb over the gear to hold it in and turned the engine over again. That's when we saw the drive gear not turning.
Posted: Fri Oct 02, 2009 5:00 pm
by JB17Atita
Hey perrib thanks for the answer
I've checked the plunger, its fine. Though, I would like to now it it's really moving when it's supposed to....
the gasket between the case and the pump is installed, the other one as welll....
Now, can you explain a little bit how measure that clearence? I don't quite get the picture....
My bearings are fine, but what if they have too much wear or if the case saddle has excesive wear? would that be cause of my trouble?
I've heated the drive gear in the past and have had no twisting what so ever... I guess a third try won't hurt, will it?
Hedrock PLZ post the explaination, that "very little oil psi" sounds almost like mine
Posted: Fri Oct 02, 2009 5:02 pm
by JB17Atita
Hedrock wrote:david58 wrote:Hedrock wrote:
This actually happened to Leatherneck on his car. The drive gear in the oil pump was spinning on the shaft that goes to the cam gear and he had very little oil psi. We changed the pump and all is well.
Hedrock explain why it was spinning is the gear keyed or pressed on?
It wasn't keyed. When David took the cover off and turned the engine over you could not tell. We only noticed it after he placed his thumb over the gear to hold it in and turned the engine over again. That's when we saw the drive gear not turning.
DUDE.....!!!!!!!! some kind of trouble, man!
thanks.... now I have to check that....
Posted: Fri Oct 02, 2009 5:12 pm
by perrib
Heating the oil pump drive gear simulates a hot engine. If the gear spins on the drive shaft you have found your trouble. How did you check your bearing clearances when you assembled the engine? The case has to slightly crush the main bearings to securely hold them.
Posted: Fri Oct 02, 2009 5:18 pm
by david58
Hedrock wrote:david58 wrote:Hedrock wrote:
This actually happened to Leatherneck on his car. The drive gear in the oil pump was spinning on the shaft that goes to the cam gear and he had very little oil psi. We changed the pump and all is well.
Hedrock explain why it was spinning is the gear keyed or pressed on?
It wasn't keyed. When David took the cover off and turned the engine over you could not tell. We only noticed it after he placed his thumb over the gear to hold it in and turned the engine over again. That's when we saw the drive gear not turning.
Seems like a keyed pressed on gear would be a lot better, than just a pressed on. I wonder why no one has designed one?
Posted: Fri Oct 02, 2009 5:22 pm
by perrib
There are a few keyed keyed ones out there.
Posted: Fri Oct 02, 2009 5:33 pm
by JB17Atita
david58 wrote:Seems like a keyed pressed on gear would be a lot better, than just a pressed on. I wonder why no one has designed one?
huh?? what is a keyed gear? pardon my ignorance
perrib wrote:Heating the oil pump drive gear simulates a hot engine. If the gear spins on the drive shaft you have found your trouble. How did you check your bearing clearances when you assembled the engine? The case has to slightly crush the main bearings to securely hold them.
If i remember correctly there wasn't that crush...
the small bearing and the one at the camshaft gear struggle to get in but the split bearing and thrust one.... think not....
Posted: Fri Oct 02, 2009 5:50 pm
by david58
JB17Atita wrote:david58 wrote:Seems like a keyed pressed on gear would be a lot better, than just a pressed on. I wonder why no one has designed one?
huh?? what is a keyed gear? pardon my ignorance
:
This is an example of a keyed shaft without the key.
This is an example of a keyed shaft with the key the gear would have to be machined to accept the key.
Posted: Fri Oct 02, 2009 9:29 pm
by JB17Atita
Nice!!!!!! woodruff key!!!
and I suppose that a pressed gear is without the key
just a smooth shaft, right??
Thanks for the pic david58
Posted: Fri Oct 02, 2009 10:27 pm
by Piledriver
Some (most? all?) CB pumps are keyed.
A touch of TIG also does wonders...
Posted: Fri Oct 02, 2009 11:01 pm
by Bugfuel
the pressed in shafts I have bothered to look at closer, have not been smooth, but "ribbed" somewhat... noit quite splined but you get the idea.
Posted: Sat Oct 03, 2009 10:50 am
by JB17Atita
Is too much bother to ask which pumps had that pressed or keyed gear??
say for example, an OEM 21mm gear pump, is keyed or pressed?
I'm on my way to check that, wish me luck...