Crank rear oil seal conversion for 1098 cc ?

[Budgie]

With regards to the above crankcase rear oil seal conversion, has anyone done this and how is it done as I currently have the engine out and after rebuilding the gearbox [ well my brother-in-law is doing it, I'm just the observer, helping hand] I'm going to be sorting out the engine just to improve some bits and pieces either wise all is fine with her except for the common oil leak in question. My brother-in-law is more than adept in this field but he's scratching his head on this one!

[Mark Wilson]

I haven't fitted one, but there have been numerous postings on here and the MG sites with mainly adverse comments. As I understand it the oil seal conversion depends on a rubber lip sealing against the unmachined outer edge of the crankshaft rear flange, and therefore doesn't work well for long. There shouldn't be a problem with the original scroll seal if the "eyebrow" housing is correctly set and if the crankcase breathing is creating negative pressure as intended.

Mark

[simmitc]

In my experience the kits are a complete waste of time and money. You will find plenty of posts agreeing with that view. One trader advised me that they seal could be fitted with the engine in situ by just dropping the sump. Complete rubbish, you need to remove the flywheel! As noted above, the design is poor and an engine in good condition will be better than a poor engine with one of the kits.

[philthehill]

I fitted the lip seal conversion on the rear of my 1400cc (1275cc) Midget engine but it was soon removed.
Whilst the idea is good the practicalities of the conversion were not satisfactory.
So long as the main bearings are good and the crankcase breathing/ventilation system is kept clear the standard set up utilising the scroll is more than adequate.
Having done the lip seal conversion and found it lacking I would not contemplate fitting a lip seal to another 'A' Series.
The lip seal conversion is over rated.
Phil

[IslipMinor]

Yes, it's interesting that Peter May Engineering, Spridget specialists, sell the lip seal conversion, but do not recommend it (especially for higher revving modified engines)!

I think the perceived wisdom of 'stay well clear' seems to be the best.

[rayofleamington]

The design was copied across from Maestro A+ engine however that has a machined surface for the seal to run on.

If you're getting the crank machined for a rebuild then it wouldn't be too hard to get them to clean up the crank in this area for the seal.. but without that I suspect it relies on luck as to whether the crank surface is OK.
If you do a quick visual check and the crank surface has lumps bumps nics and cuts then the seal isn't going to defy nature - it will get wrecked.

[Declan_Burns]

I have the seal on my car (1098) and it has worked well over the years but you really need a good machined crankshaft flange. I fitted one on the 1275 Midget engine I rebuilt recently but again the crank flange was polished by the previous owner. I have not yet run the engine.
Fitting these kits is not a simple bolt on job. I had to carefully machine the spacer supplied with the kit to get it to fit and you have to ensure that the seal is properly centred.
One option which can work is to use an SKF Speedi Sleeve on the crank flange and use a Viton seal instead of the seal supplied. This can be done and is a lot easier with the engine on the bench and access to good machinery-otherwise I would not recommend it and would, as mentioned above, pay particular attention to the engine breathing. The whole issue is very much "hit and miss" and most people I know have missed rather than hit. For that reason I didn't fit one on my MG TD. These cars are notorious leakers. The kit being very expensive too.
I fitted a PCV valve which reduced the leak from a torrent to a trickle and added a simple drip tray.
Just my opinion.
Regards
Declan

[Declan_Burns]

The drip tray
Regards
Declan

[philthehill]

As regards the 1275cc lip seal conversion.
The problem with this seal kit is having to install the spacer that fits between the rear of the crankshaft and the flywheel.
You have to fit the spacer to get the flywheel to clear the lip seal housing - that causes a problem in that it lifts the 1275cc flywheel off the crankshaft register - you are then left relying on the two dowels to locate the flywheel.
Also the spacer supplied in the kit fitted for my engine was subsequently found to be made of quite soft metal which deformed in use and allowed the flywheel to come loose even though the bolts were torqued up correctly and the fitment of the seal kit was undertaken with the utmost care.
Thankfully I realised what had happened and stopped the engine immediately - because of that action there was no real damage caused but it meant that my sprint event had to be cut short and the car taken back home on the trailer and an engine re-build undertaken.
As I said above the idea is good but the practicalities of fitting the kit are not.
If the kit is to be fitted the spacer must be of good quality (hard) steel and true - most importantly the crankshaft flange where the lip seal runs must be machined or at least given a absolute smooth surface.
The benefits of fitting the lip seal are not worth the effort and cost involved.

[Declan_Burns]

Thanks Phil,
I remember you pointed that out to me at the time and I did make up a spacer from a harder metal.
I agree not worth the hassle.
Regards
Declan

[Budgie]

Ok thanks for the answers and point taken although I guessed the answer would be a resounding "leave well alone". Just trying to do the best for the engine while it's out on the bench. As for the elusive oil drip, I have checked and cleaned the breather pipe etc and covered all the issues relating to the possible causes of this issue but so far to no avail hence my desperation with the conversion fix so I'm still no better off which is a shame seeing as I have no intention of fiddling with the engine once it's back in her resting place .

[philthehill]

Make sure that the oil pump cover is fitting correctly in the rear engine plate - if it is not it can weep.
Another point to look for - the rear cork seal flange may be coming apart from the main body of the sump.
Make sure that the faces of the block and rear engine plate are spotless on assembly as any dirt between the two can cause the engine plate to not seat and leak oil.

[Budgie]

Ok I'll make sure I check them out .As a matter of interest the seals from the sump were not cork but rubber when I removed them!

[philthehill]

The later 'A' series engines did have a neoprene/rubber gasket/packing fitted and it is possible to cut that gasket/packing down to enable fitment to the earlier engines.
Personally I have never had the need to use other than a cork gasket/packing to seal the front or rear of the sump even with 1275cc engines.
The secret is to ensure that the front and rear gasket/packing are the correct lengths and covered in grease. The sump side gaskets should be greased and placed on the block to sump flange and the sump with front and rear gaskets/packing installed offered up to the block. Fit the sump bolts and progressively tighten until the sump is fully home.
If care is taken on assembly there will be no leaks.
There is absolutely no need to use gasket goo or any other sealant.
Phil

[Pucketsport]

Hi Declan
I am really impressed with your drip tank, it seems like a great solution for a leak that is not too severe. I'm curious, what mileage do you cover before it needs draining ?
I will be pursuing all avenues to correct the leak issue my car has as per the guidance / advice from Phil but ultimately I don't want any dripping at all. Have you sealed the gearbox to engine interface to ensure that the leak path is restricted to the gearbox " breather"
My fellow Engineers and I were having a bit of a laugh as we thought about how far you could take this idea. ( drip tank oil level warning light, electric pump to empty oil at a convenient point ......etc

[Declan_Burns]

Pucket,
Read through this thread and I mentioned the PCV valve installation.
viewtopic.php?f=4&t=68097#p621709
Before I installed the PCV valve I had to empty the drip tray about every three weeks. With the PCV valve I only had to empty it once last season. That basic drip tray , originally designed and sold by the late David Pelham, is dimensioned to fit the MG XPAG engine. Nowadays the basic tray is made by Bryan Purves and I convert them from a bottom to a side exit (for ground clearance and access reasons) and fit a level indicator plus a baffle made from a windscreen insect sponge. That stops the oil from swishing around. The side exit is easily accessible on the MG without actually crawling under the car. No other sealing required. That drip tray could be re-modelled to fit the Minor where you do not have exhaust clearance issues like on the XPAG engine.
The PCV valve is well worth fitting. Be sure to get the original valve-see principle drawing below.
Regards
Declan

BTW you could use the tapping point (Model aircraft tank nipple!) for the tray level indicator to connect to a pump or negative pressure source to keep the tray empty. I intend to do some experimenting with that this season.

[Pucketsport]

Thanks very much for the detailed response Declan. I like the mods you have made for ground clearance. Regardless of how effective my attempts to fix the leaks are I think I will pursue a similar device. By the way that aluminium welding is really good.
What material is that insect sponge made of ? obviously something resistant to oil ?

[Pucketsport]

I have one more question for the members. If it is found that the oil leak from the scroll seal on the engine is excessive, how does one rectify this ? I heard we need to skim the bearing caps and line bore ? Is that correct ?

[Declan_Burns]

Pucketsport,
It is a hard windscreen insect removal sponge made by Nigrin. No problems with oil.
Regards
Declan

[philthehill]

If you get to the point of having to skim the bearing caps and line bore the crankshaft bearing housings then there is something seriously wrong with the engine. I personally would throw the engine away and start again. The cost of having the skimming and line boring undertaken makes the job untenable. Only if you are having new bearing caps fitted should you require the main bearing caps to be line bored.
If the crankshaft main bearings are good then the crankshaft will remain concentric to the scroll and the scroll will return oil to the sump. When the crankshaft main bearings are worn (especially the rear main) the crankshaft will not be concentric to the scroll so allowing the clearances at the scroll to be excessive and then oil will then work past the scroll.
With the crankshaft main bearings in good condition any oil that gets past the scroll will arrive at the crankshaft oil throwing ring at the rear of the scroll and be thrown off the ring and be caught by the catcher trough (which is in two half's, one part is cast into the rear main cap and the other part is the detachable top half of the catcher trough attached to the rear of the block) and drain down back into the sump via the drain holes in the rear main cap.
Early 'A' Series engines had a drain tube from the rear main cap down to normal oil level in the sump. This allowed all oils arriving at the catcher trough to drain down into the sump well away from the sump rear seals.
As well as having the crankshaft main bearings and crankshaft in good condition it is important to have good engine breathing so as not to create pressure in the crankcase which may overcome the return scroll.