[xk-engine] Rebuild of an S3 4.2: Rear main oil seal upgrade? Y/N

This is continuing the thread of my S3 4.2 rebuild. After
mic’ing the bores and the pistons, as well as side ring
clearances an .020 overbore and new pistons (I selected 8:1
Mahle short skirts in this case) are necessary.

The crank has been ground to .010 over on mains and rods. A
question remains for the crank; whether to install an
aftermarket rubber rear main oil seal kit, as sold by
several suppliers. Does anyone have experience with these?
Know of successful or unsuccessful installs? The kit I am
considering is from XKs Unlimited. Any opinions on the best
supplier for this kit?

I had one machine shop tell me that they stick with the rope
seal because of only 50/50 success with the rubber seal kits.

Thanks for any insights,–
Matt Curry, '75 XJ6 Coupe
Seattle/WA, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

//please trim quoted text to context only

In reply to a message from MJC 75 XJ6C sent Fri 3 Jul 2015:

If you go for the mod it normally involves matching the
crank to allow for the new system. At which point it is not
reversible. There is little wrong with a properly installed
rope seal. These engines are never ever leak free but can be
made acceptably dry with care and attention during a
rebuild. There is much written on the etype forum on this
subject.–
The original message included these comments:

This is continuing the thread of my S3 4.2 rebuild. After
mic’ing the bores and the pistons, as well as side ring
clearances an .020 overbore and new pistons (I selected 8:1
Mahle short skirts in this case) are necessary.
The crank has been ground to .010 over on mains and rods. A


Phil.D 3.8 etype, XJR6, XK150 FHC, 2.2 diesel Xtype
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

//please trim quoted text to context only

In reply to a message from Phil.Dobson sent Fri 3 Jul 2015:

In Chris Rooke’s book, ‘‘E-TYPE JAGUAR DIY’’ I believe the
new seal has to be cut in half…then installed via super
glue…–
Mitchell Roe
Hasty, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

//please trim quoted text to context only

In reply to a message from MJC 75 XJ6C sent Fri 3 Jul 2015:

In 50 years of building XK engines I’ve never had a seal
leak, just do it by the bool–
The original message included these comments:

I had one machine shop tell me that they stick with the rope
seal because of only 50/50 success with the rubber seal kits.


850225/679,1E21003,2W2001BW,JNAEY3AC100218,SAJNV4841KC156072
MELTON, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

//please trim quoted text to context only

In reply to a message from Phil.Dobson sent Fri 3 Jul 2015:

Hi I’v just done it on a 1960 3.4. Have now done about 200
miles not a sign of an oil leak any where. And yes there is
oil in the engine. The worry now is that after many years of
owning Jags is remembering to check the oil.
The puddle on the floor always reminded me before.
Roger–
spitzstick
hobart, Australia
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

//please trim quoted text to context only

In reply to a message from MJC 75 XJ6C sent Fri 3 Jul 2015:

IF you go with lip seal make sure you put split at top.lip
seals are not in two parts, they are rubber enclosed on one
side. Also make sure the rear seal housing is accurately
machined concentric to the crankshaftthat has to have the
scroll removed.–
Nigelplug
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

//please trim quoted text to context only

I may be wrong but I think this kit was invented by Bill Terry and he made a nice video on YouTube.

I like the idea but considering the machine work and the cost of the kit itself I’m considering this very carefully. That couple with Chris Rooke’s superglue experience - and his comment that you don’t know if all is right until you fire the engine - is plenty of cause for careful consideration.

I’m still considering :grinning:

I did the 2 pc rear main seal conversion during a 1967 4.2L DOHC engine restoration. Although we made numerous performance upgrades, the seal upgrade was an interesting operation. We have done these upgrades on numerous types of engines from various manufacturers, so I was familiar with what needed to be done. We made the aluminum housing in-house, and did all the block machine work. My crank grinder modified the crankshaft to our specifications. The job is time consuming so labor is a little pricey, but the parts and materials are inexpensive. Both my customer and I were very satisfied with the results. Not one drop of oil leaked during the dyno testing, and my customer hasn’t told me of any leaks. I highly recommend this modification whenever possible on any engine. IMO, rope seals are leakers. I know some of the old timers love rope seals, but technology has made them obsolete. They are cheaper, but far less efficient. Just my two cents.

I went for the one piece lip seal which involved a machined down flywheel flange, with the crank drilled and threaded for a new CNC machined flywheel , about £1100 but no leaks…

We initially concerned that option. We went with the 2 pc option because we felt the 1 pc option reduces the strength of the crankshaft at the rear main area. With the 2 pc, the original basic design remains intact. That, plus the 1 pc option is quite a bit more expensive. Again, just my two cents.