16 replies to this topic

[mad4classics]

Just priming the oil pump by back filling at the banjo bolt and turning over backwards with the transfer casing not fitted. I notice that oil appears at the bottom of the pump in the semi-circular cut-out where it mates with a hole going through the block.

 

Never thought about the rear cam bearing lubrication before; The rear bearing only seems to get lubricated by the small hole in the pump face - is this what I'm seeing as a "leak" when priming the pump???

 

I've pictured the old pump face ; is there sealing between the cam bearing at the bottom where that cavity is or does oil just drain out there?

 

It's a new pump and gasket on a 998 A+ block; just want to understand if this is normal or a gasket problem? (Sorry - getting a bit paranoid as the build nears completion)

 

 

Attached Files

•  Screenshot from 2022-02-15 09-24-58.png   178.4K   3 downloads

[nicklouse]

Are you sure the bolts are not too long?

[mad4classics]

Are you sure the bolts are not too long?

Bolts I've used are 1 1/2" ; so shouldn't be. There seemed to be at extra 1/82" I could screw the bolts in without the pump.

 

https://www.somerfor...d-14-unf-x-1-12

 

Don't know if I should take it all apart again to look.....

Edited by mad4classics, 15 February 2022 - 12:19 PM.

[GraemeC]

You need to physically check them as the hole depth and oil pump thickness varies.

[mad4classics]

You need to physically check them as the hole depth and oil pump thickness varies.

Yep, did that - looks like I'll have to take it apart and find a new gasket.

 

That cut out at the bottom of the oil pump doesn't seem to get sealed by the gasket?

Edited by mad4classics, 15 February 2022 - 12:25 PM.

[GraemeC]

No, the gasket doesn't seal that cut out.

From memory this is not a pressurised feed to the cam bearings but the return path for the oil (it is delivered by a hole in the middle of the cam bearing directly onto the journal)

[Pigeonto]

Graeme is right.about the gasket There's no oil at that point to need sealing.

However the hole IS the feed to the cam bearing. And doesn't it feed !!   I once tested a short block for oil pressure prior to building up having converted it from auto just to make sure I'd got it right.. The pressure makes the camshaft into a ram effectively  and forces it very hard against the  triangle plate at the other end. That's what causes wear on the inside of the plate

Edited by Pigeonto, 15 February 2022 - 12:58 PM.

[mad4classics]

No, the gasket doesn't seal that cut out.

From memory this is not a pressurised feed to the cam bearings but the return path for the oil (it is delivered by a hole in the middle of the cam bearing directly onto the journal)

 

On the rear camshaft bearing there is no direct feed from the filtered oil; it seems to be feed only by the small hole in the oil pump with unfiltered oil.

 

Graeme is right.about the gasket There's no oil at that point to need sealing.

However the hole IS the feed to the cam bearing. And doesn't it feed !!   I once tested a short block for oil pressure prior to building up having converted it from auto just to make sure I'd got it right.. The pressure makes the camshaft into a ram effectively  and forces it very hard against the  triangle plate at the other end. That's what causes wear on the inside of the plate

This is what I can't make out; with the feed effectively to the rear face of the camshaft  - will this oil be seen coming out at the bottom when I back feed the pump since there is no seal at the bottom point; what stops it draining out as it feeds oil to the rear journal? Or do I need to take it apart to find out what's going on?

Edited by mad4classics, 15 February 2022 - 01:18 PM.

[Pigeonto]

I don't have a gasket to hand but if you look at the circular mark left by the gasket, it's clear that it is above the recess so oil cant escape into the recess.

If oil is escaping then the gasket is being prevented from doing its job by not being clamped for whatever reason

[mad4classics]

I don't have a gasket to hand but if you look at the circular mark left by the gasket, it's clear that it is above the recess so oil cant escape into the recess.
If oil is escaping then the gasket is being prevented from doing its job by not being clamped for whatever reason

So you don't think oil coming out of the small hole in the pump should be seen draining out at the bottom when back feeding the pump. It's a new gasket but looks like it'll all have to come apart again!

Edited by mad4classics, 15 February 2022 - 01:45 PM.

[mad4classics]

OK, ...

 

1. Removed oil pump; cleaned out threadlock from threads;

2. Shortened bolts by about 1/32" - now have 1/16" under oil pump height when fully crewed in;

3. Fitted new paper gasket greased both sides (very thin this gasket!!!);

4. Applied Loctite 243 0n threads - torque to 8ftlbs

5. re-primed pump.

 

Seems better, but I can't actually put my finger on exactly what the problem was - what more can I do?

Attached Files

•  Screenshot from 2022-02-15 15-32-07.png   152.68K   4 downloads
•  Screenshot from 2022-02-15 15-31-03.png   228.35K   5 downloads
•  Screenshot from 2022-02-15 15-32-43.png   150.72K   5 downloads
•  Screenshot from 2022-02-15 15-33-13.png   174.99K   5 downloads
•  Screenshot from 2022-02-15 15-33-46.png   163.7K   3 downloads
•  Screenshot from 2022-02-15 15-34-33.png   148.19K   3 downloads
•  Screenshot from 2022-02-15 15-35-41.png   228.25K   3 downloads

Edited by mad4classics, 15 February 2022 - 03:50 PM.

[GraemeC]

http://www.nonlintec...te/lubrication/

[mad4classics]

http://www.nonlintec...te/lubrication/

Thanks for that - the rear cam bearing is supplied direct from the oil pump with unfiltered oil in the a-series engine.

[Pigeonto]

No  ! It shouldn't but appears you've sorted it now 

I don't have a gasket to hand but if you look at the circular mark left by the gasket, it's clear that it is above the recess so oil cant escape into the recess.
If oil is escaping then the gasket is being prevented from doing its job by not being clamped for whatever reason

So you don't think oil coming out of the small hole in the pump should be seen draining out at the bottom when back feeding the pump. It's a new gasket but looks like it'll all have to come apart again!

 

[mad4classics]

No ! It shouldn't but appears you've sorted it now

I hope so; still a bit dubious about the thickness of the gasket it measures ~0.010" (0.250mm) thick - is that the standard paper thickness supplied these days ???

Edited by mad4classics, 16 February 2022 - 02:11 PM.