Mk3 Oil Non Return Valve

[maaseyracer]

Amidst having the engine apart on my Mk3 I misplaced the oil non return valve. I ordered a spare oil non-return valve, (just the piston part number 06-6199). Upon receiving the new part (and a new seal) i am having some issue getting the case to fit. I end up with an 1/8th inch gap around the case if I remove the non-return valve the case closes. After lots of puzzled swearing. making a non-return valve tool to hold it in place while installing it, using some clay to see what the gap is, fitting the cover a couple dozen times, and killing the better part of a day, I think what I am seeing is that the new valve is too long.

Does any one have a properly fitting 06-6199 that they can measure the length of?

When the valve is depressed into the timing cover should the oil passage be exposed on the sides of it? Or am I missing something that was much more obvious in previous dealings with this?

 

[L.A.B.]

When the engine starts the oil pressure should force the plunger back far enough for the oil to flow into the timing cover. If the plunger won't allow the timing cover to be fitted then there's something wrong.

 

[marshg246]

Amidst having the engine apart on my Mk3 I misplaced the oil non return valve. I ordered a spare oil non-return valve, (just the piston part number 06-6199). Upon receiving the new part (and a new seal) i am having some issue getting the case to fit. I end up with an 1/8th inch gap around the case if I remove the non-return valve the case closes. After lots of puzzled swearing. making a non-return valve tool to hold it in place while installing it, using some clay to see what the gap is, fitting the cover a couple dozen times, and killing the better part of a day, I think what I am seeing is that the new valve is too long.

Does any one have a properly fitting 06-6199 that they can measure the length of?

When the valve is depressed into the timing cover should the oil passage be exposed on the sides of it? Or am I missing something that was much more obvious in previous dealings with this?

Are you using the MK3 seal?

The valve should push into the cover far enough to let the oil pass (yes to you last question) - are you sure you're using the right spring and will the valve move freely in the hole without the spring?

No tool is required to install it - just a length of wire. You put the wire through the rocker feed hole, push the valve in far enough that the wire can go past it, and put the cover on. Then, pull out the wire.

 

[L.A.B.]

I will ask what could be a daft question but you are fitting the plunger with the closed end to the (Mk3) pump seal and the open end to the spring?

 

[maaseyracer]

After staring at it long enough after posting this it just did not look right so i cleaned it for a 50th time, broke out magnifier on my phone. I was not sure about it, but I said screw it and busted out the drill... Found a spring as well. Once I saw the spring I tried grabbing it out with everything I could and finally went for the easy out. Took an insane effort to get it out. No idea what when on here. I am going to need to free up some time to get this one setup in the mill. Probably need to sleeve it.

 

[L.A.B.]

Imgur pictures aren't viewable in the UK any longer so I don't know what you are showing us.

I was not sure about it, but I said screw it and busted out the drill... Found a spring as well. Once I saw the spring I tried grabbing it out with everything I could and finally went for the easy out. Took an insane effort to get it out.

I really don't understand this at all. Do you mean you drilled out the plunger or plunger housing?
With the plunger removed the spring should fall out.

 

[cliffa]

Imgur pictures aren't viewable in the UK any longer so I don't know what you are showing us.

I really don't understand this at all. Do you mean you drilled out the plunger or plunger housing?
With the plunger removed the spring should fall out.

I can see the picture, and what I think is the “missing” plunger was stuck in the case all along. @maaseyracer is that correct?

Edit: I copied the picture, this is it…

 

[L.A.B.]

Thanks, yes that looks like the plunger so that would explain it.

 

[maaseyracer]

Thanks, yes that looks like the plunger so that would explain it.

It was the plunger. Vey much jammed in there, air hose on the vent had no effect. Bore is trashed, will try honing it out, but I am skeptical.

 

[cliffa]

It was the plunger. Vey much jammed in there, air hose on the vent had no effect. Bore is trashed, will try honing it out, but I am skeptical.

As long as the new plunger can travel freely in the bore it doesn’t really matter if it’s scored etc. as it’s only purpose is to keep the plunger in line with the pump grommet. As soon as the pump is developing pressure the plunger backs into the bore, and oil flows into the side gallery.

 

[kommando]

The plunger is prone to jamming in the MK3 cover, it should have been a ball like AMR but you have to work with what you have. I would leave the bore as is after cleaning it out of any debris and honing it smoother, a loose fit means the plunger is less likely bind. But I would also increase the plunger front plus back radius and then polish them smooth, again to reduce the risk of the plunger hanging up. Its the front face of the plunger resting against the rubber seal that stops the oil from wet sumping. A plunger with a close fit to the bore will not reduce wet sumping.

 

[maaseyracer]

The plunger is prone to jamming in the MK3 cover, it should have been a ball like AMR but you have to work with what you have. I would leave the bore as is after cleaning it out of any debris and honing it smoother, a loose fit means the plunger is less likely bind. But I would also increase the plunger front plus back radius and then polish them smooth, again to reduce the risk of the plunger hanging up. Its the front face of the plunger resting against the rubber seal that stops the oil from wet sumping. A plunger with a close fit to the bore will not reduce wet sumping.

A dissimilar metal would a good option as well, though not sure I want to machine this case, fixturing it looks like no fun. I have a piece of 932 bronze sitting around, that is an option.

However, the option I am leaning towards, is to hone the bore out then apply a graphite coating to the bore to tighten it back up.

Wet stumping really has not been an issue, other than this device put in place in an attempt to stop it.

 

[maaseyracer]

I was able to successfully get the burr out of the bore. I had a high speed steel that I had ground for something else that worked well enough. I then cleaned the bore up about with a ball hone (brush hone, whatever you want to call it). I really did not want to bore and sleeve this, every time I test fit the steel plunger I was able to get piston/valve to stick and hang. After some prolonged procrastination, I got an idea... No sleeve, use the the 630 bronze (i was sure it was 932 earlier) to make a bronze piston, then use that graphite piston coating stuff to line the bore to help fill in imperfections and or low spots. No fixturing, quick enough job on the lathe. Fits like it should. I am going lap the face of it on some fine sandpaper and call this one good, unless someone has a reason to change my mind on this. I was even able to my new homemade tool to use on this one.

 

[cliffa]

I was able to successfully get the burr out of the bore. I had a high speed steel that I had ground for something else that worked well enough. I then cleaned the bore up about with a ball hone (brush hone, whatever you want to call it). I really did not want to bore and sleeve this, every time I test fit the steel plunger I was able to get piston/valve to stick and hang. After some prolonged procrastination, I got an idea... No sleeve, use the the 630 bronze (i was sure it was 932 earlier) to make a bronze piston, then use that graphite piston coating stuff to line the bore to help fill in imperfections and or low spots. No fixturing, quick enough job on the lathe. Fits like it should. I am going lap the face of it on some fine sandpaper and call this one good, unless someone has a reason to change my mind on this. I was even able to my new homemade tool to use on this one.

If I was making one and I knew the nipple on the grommet was perfectly central to the plunger, I’d machine the plunger to have a shallow point or maybe even a small point in the centre to block the grommet more efficiently.
Anyway, that’s just me, but I would suggest chamfering the front and rear of the plunger, and mirror polishing it.

 

[maaseyracer]

If I was making one and I knew the nipple on the grommet was perfectly central to the plunger, I’d machine the plunger to have a shallow point or maybe even a small point in the centre to block the grommet more efficiently.
Anyway, that’s just me, but I would suggest chamfering the front and rear of the plunger, and mirror polishing it.

I lapped it on a diamond file and then 2000 paper for the final. the photo makes the finish look way worse than it is, chamfer is there as well, very similar if not more pronounced than on the steel version. Line boring this would not be a fun machine setup, not sure there is anything to gain, it is either opened or closed and the seal shoudl be able to make contact the surface easily.

In the future I may resleeve the cover, or ream it and make another valve, but that all depends on how this wears. The nice part too is that I could adjust the size a bit if I needed to.

 

[mdt-son]

I see no benefit in using 630 bronze, which has a significantly lower Young's modulus than steel (120 GPa vs. 210 GPa). UTS isn't too bad (760 vs. ~1000 MPa).
When making my new plunger, I will use 01 tool steel quenched (100MnCrW4, DIN 1.2510). UTS is about 1600 MPa. I will _not_ put a taper on the plunger's open end, that's asking for trouble.

- Knut

 

[maaseyracer]

I see no benefit in using 630 bronze, which has a significantly lower Young's modulus than steel (120 GPa vs. 210 GPa). UTS isn't too bad (760 vs. ~1000 MPa).
When making my new plunger, I will use 01 tool steel quenched (100MnCrW4, DIN 1.2510). UTS is about 1600 MPa. I will _not_ put a taper on the piston's open end, that's asking for trouble.

- Knut

I am all for using tool steel where appropriate believe me. However the issue here is that whatever mild steel is in the bore is prone to galling which will catch the piston, tool steel might make the problem worse as it will be significantly harder then the bore. Sleeve the bore with bronze and and hardened 4140 or tool steel makes sense for a piston material. It would not surprise me if the grade of bronze I am using is harder than the stock piston or the bore as well.

Otherwise tool steel does not solve the issues with the bore material galling and sticking trapping the piston. The stock pistons is not really under much load at all as the spring pressure is not much, and it is not going to distort.

One of these days I will make a fixture to capture the case to cut out and sleeve the bore with bronze, and go back to a stock piston or go back to a steel one.

 

[marshg246]

I am all for using tool steel where appropriate believe me. However the issue here is that whatever mild steel is in the bore is prone to galling which will catch the piston, tool steel might make the problem worse as it will be significantly harder then the bore. Sleeve the bore with bronze and and hardened 4140 or tool steel makes sense for a piston material. It would not surprise me if the grade of bronze I am using is harder than the stock piston or the bore as well.

Otherwise tool steel does not solve the issues with the bore material galling and sticking trapping the piston. The stock pistons is not really under much load at all as the spring pressure is not much, and it is not going to distort.

One of these days I will make a fixture to capture the case to cut out and sleeve the bore with bronze, and go back to a stock piston or go back to a steel one.

I'm a little confused - not a metallurgist. MK3s seem to work just fine in most cases and I often add MK3 timing covers (from AN) to pre-MK3s without problems. I've never seen a problem with one. Any idea how this problem started?

 

[mdt-son]

Otherwise tool steel does not solve the issues with the bore material galling and sticking trapping the piston. The stock pistons is not really under much load at all as the spring pressure is not much, and it is not going to distort.

The occurrence of a locked plunger does not correspond to galling in my view. Galling is defined as unexpected adhesion between two or more sliding surfaces, causing cold welding. Galling is unlikely, because: (1) Surfaces are lubricated. (2) there is clearance between plunger and housing initially, and (3) the plunger hardly moves - the prerequisite for severe friction and cold welding is not met, as I see it.

In my opinion, the problem is caused by hydroforming of the plunger subjected to a peaky dynamic oil pressure. I don't share your view of the plunger not being able to distort!

- Knut

 

[dobba99]

At 100 PSI the plunger is subject to approx 15Lbs of force, and that force is spread evenly over the surface of the plunger. 15 Lbs is not able to 'hydroform' the plunger. They get stuck because of the slight bevel at the bottom of the bore (from manufacture, they probably had a worn reamer to do this job) and the chamfer on the end of the plunger being too small, then, when left stuck, get gunged up as well. A good oil pump with the clearances closed up and the PRV set correctly, will achieve something in the region of 40 -50 PSI
If your plunger looks like it is concave, its because someone has tapped it with something (maybe a hammer and punch) hoping to shock it free. Hydro forming is done with pressures in the thousands of psi.
Drill and tap, pull it out, clean the bore, purchase ( or make) a new plunger, ensure sliding fit in bore. Fit and forget. Job done.