[xk-engine] Engine half dismantled, now what?


(Eric Feron) #1

Hello all,

after a long absence, I finally took the sump and timing
chain cover off.

Here is a little video of the insides:

I would love some advice on:

  • timing chains and tensioners: replace or leave as is
  • oil pump / distributor gear: looks worn to me, Replace?
  • crankshaft, rods, pistons : leave as is or go all the way?

Thank you for your help.
E–
1975 XJ6C - LHD
Sunnyvale, United States
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(carsoncitysmith) #2

In reply to a message from Eric318 sent Thu 1 May 2014:

What’s your budget? What’s your goal? It is just time and
work and money and satisfaction.
How many miles are on it already?
What do the bearings look like?
Was there any metal in the bottom of the sump?
Is there any slack in the timing chain?
Are the tensioners worn?
Is there a ridge at the top of the cylinder bores?
Has it been rebuilt before?
Do you want this particular motor or would some other motor
do as well if it was in better shape?
What does it look like inside the water jacket?
Do you want to check the block for cracks?

I know I could use a rebuild myself, so these are all the
things I think about. I can’t tell you the answers though.

P.–
Peter J. Smith, 1966 3.8S MOD
Carson City Nevada, United States
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(Eric Feron) #3

In reply to a message from carsoncitysmith sent Thu 1 May 2014:

Thank you P.

This is a great set of questions to start with.

I want that engine back in its own car.
It sounds like the way forward is to inspect the timing gear
and bearings further… :slight_smile:

The c/head is on the shelf, refurbished by Coventry West 2
years ago, untouched.

Also awaiting is a GM gearbox and the conversion kit from
Johnscars.

Aiming for a good engine for normal use and reasonable
money.

Will keep you updated.

Cheers,
EF–
1975 XJ6C - LHD
Sunnyvale, United States
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(Rob Reilly) #4

In reply to a message from Eric318 sent Thu 1 May 2014:

Certainly you should start with more disassembly and
cleaning of parts.

In addition to Peter’s list of questions, I’ll add a list of
the order in which I would spend your money.

complete gasket set
oil filter
core plugs
spark plugs, wires, distributor cap
piston rings (evaluate pistons for excessive wear on skirts,
replace if damaged on top)
connecting rod bearings (evaluate crankshaft for scoring and
possible regrind)
timing chains
timing chain tensioner pads
main bearings
distributor driven gear
evaluate piston bores, use Flex-hone for light cleanup (or
rebore for oversize pistons)
block cleaning
timing chain sprockets
distributor shaft bushing

No doubt I’ve forgotten something.
You may read about timing chain stretch. Its not quite a
true way of expressing it, what happens is there are
something like 100 links and if each link pin is worn .0001’’
the whole chain will be worn .010’’, each pin .0002’’ is .020’’
on the chain, and so on.
So keep at it and this forum will help.–
XK120 FHC, Mark V saloon, XJ12L Series II, S-Type 3.0
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(carsoncitysmith) #5

In reply to a message from Rob Reilly sent Fri 2 May 2014:

I read a good tip somewhere on judging the wear of timing
chains.
Take it out and hold it up sideways and see how much it
droops. Each link has some slack, very little when new and
more with wear. As you hold the chain sideways the cumulative
slack results in droop.
No, I can’t tell you how much droop is ok, but you will get
some feel for it. Maybe find a new chain and hold that out
for comparison.
P.–
Peter J. Smith, 1966 3.8S MOD
Carson City Nevada, United States
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(Robin O'Connor) #6

Hi Eric

From Wikipedia is the following calculation to determine the overall % of
chain wear

%=((M-(SP))/(SP)*100

M = the length of a number of links measured

S = the number of links measured

P = Pitch

The recommended wear for an adjustable set up is 3%

Hope this information helps in determining your choice.

Regards Robin O’Connor
'92 XJ40 4.0 Ltr
'66 'S’Type MoD
'75 XJ6 4.2 LWB
Auckland NZ

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(sidsnot) #7

In reply to a message from Eric318 sent Thu 1 May 2014:

You need to strip more …

If no bore lip and you can see a crosshatch pattern in the
bores you could forgo piston removal if it passes the ‘raw
gas in the bore test’ that will give you an indication of
the rings condition. But no matter what the oil pump should
be stripped and inspected and the main and rod bearings
inspected for wear [if oversized marked you know its been
rebuilt before] the dist.oil pump gear is ok ‘just check for
burrs’
REMOVE THE CHAINS AND REPLACE.along with the guard rails/and
adjuster. Black hammerite paint will work good.

When the engine is this far disassembled I dont see the
point of not looking at everything.–
sidsnot
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(Eric Feron) #8

I wanted to close the loop on this thread after so many years.
It turned out that the block was cracked between every . single . cylinder !!!
I will soon start dismantling my second engine (other thread).
If anyone needs s/h engine parts… Timing cover anyone? If not it will all go to recycling or scrap.


(Pat Harmon) #9

What engine do you have? I need a set of 3.8 valve covers.

Pat H


(Eric Feron) #10

70’s XJ6 SII, sorry.


(Eric Feron) #11