The Jensen Owners' Club

I currently have the car up on my lift sorting out some gearbox issues and it got me thinking if it's worth dropping the sump and checking big end and mains as I get the 'flickering' oil pressure light.
I'll change the oil pump anyway (or check and blueprint it) but I'm considering putting some new mains and big ends assuming the current ones are tired

A set of mains and big ends is cheap enough to replace until such a time that I can do it properly and yes, when I do it properly I'll get it all machined but for now...

So..my question is what can be done from underneath if the sump is removed?

Some of the mains I've seen have #1 and #5 with a ridge meaning to walk them out may be tricky?
Any advice?

I don't recommend replacing the bearings without replacing the crank at the same time. It is never done on these engines as a routine or maintenance job. If there is a worn out bearing there is a worn out journal on the crank to go with it. Has your engine ever had the timing chain replaced? The original cam gear has plastic teeth that will disintegrate over time and clog the oil pump pickup screen. You may want to check that out.

Yes you can change the big ends and main bearings in situ, messy job but can be done, if your bearings are a little worn but the crank is still mint its actually very worth while you doing it, after you replace each bearing set check that your engine is still rotating ok, the fortunate thing with a interceptor is no crossmember in the way so acces really is very good,,

Thanks guys,

I`ll pull the caps tonight and have a look and get an idea of the state of the bearings (and sizes etc.).

Duncan...do you know if #1 and #5 are do-able as well with the engine in-situ? These are the ones with the thrust washer/flange?

I`m certain the timing chain has been replaced, but I`ll be able to check whilst the sump if off so thanks for the heads up.

AndrewP wrote:Thanks guys,

I`ll pull the caps tonight and have a look and get an idea of the state of the bearings (and sizes etc.).

Duncan...do you know if #1 and #5 are do-able as well with the engine in-situ? These are the ones with the thrust washer/flange?

I`m certain the timing chain has been replaced, but I`ll be able to check whilst the sump if off so thanks for the heads up.

Hi

its the number 3 that has the thrust washers as part of the bearing, and yes you can do them in situ,you may have to crack all five main bearing cap bolts of maybe 2 turns to just give you a little more clearence to rotate the bearings out then new in, you will have to remove the rear seal carrier to get the no 5 main cap off it is held with two 3/8 head twelve point headed bolts you need a slim socket for those or grind a socket down,, while your at it as mentioned make sure your oil pickup is pefecctly clean, and you might as well fit an oil pump, they are not bad money, its all very worth doing if your crank is not hurt, i have done this on many engines and polished the crank with emery cloth sometimes needs must,,

Thanks Duncan,

Pulled #3 main and a big end last night and the big end looks ok with a few pickup marks, but the main is definitely past it and coppered.
Interestingly, it has what looks like the original Mcquay Norris mains in still..but +030. I'm assuming it has been rebuilt as I would hope they didn't deliver these motors already 030 undersize.

Anyway ..thanks for the info..I've already had the multiple transmission fluid showers, so the oil drips from the engine just add to the character building experience!

Thanks again

Andrew

Got any pictures of the bearing shells as removed?

Will do over the weekend once I have the old ones out and the replacements in.
Clevite mains and big ends are pretty inexpensive so as long as its not a major issue and given the mileage I do in the Jensen (<5k per year) then it should see it through to a proper full rebuild when funds allow.
I think the issue when that time comes that I will face is the crank is really at its limits at +040 already so a replacement may be required as I don't think +050 or +060 are available.

Will see how the weekend pans out. It's too hot in the day here at the moment as we've have 5+ days of over 35 degrees, peaking at 40 today so I'll be staying cool and working in the cooler evenings getting eaten alive by the mozzies

OK, so have changed the mains and big ends yesterday evening.

The good news is that it wasnt overly difficult. A bit mucky and some of the bearings didnt want to come out easily, but I ended up making up a bearing removal tool out of a dome head screw and bending it to fit into the oilway so as you rotate the engine, it pushes the upper bearing out, or helps drive the new one in.
It helps to slacken all the main bearings to allow the crank to drop slightly also.
Big ends were easy in comparison. You can lift the piston in the bore (I used the handle of my hammer to tap the underside of the piston up a bit) and then remove the upper bearing, and the bearing pops out of the rod and it falls on your head.

So, what did they look like?...As expected, the thrust faces were showing signs of wear, so it was well worth doing. For $100 AUD all up, delivered a set of fairly mundane Clevite tri-metallic big ends and mains is good value. Im sure there are more exotic and expensive options out there, but the engine is relatively un-stressed and so I`ll go with this until I get the motor on a stand and see whats what for a proper re-built.

So this was the big ends..8 is left, 1 is right.
Mains were a little more tired.
Thrust face (lower) showing signs of copper so time to change.

Now...

The million dollar question. As Duncan (Cannonball) mentioned, to get to #5, the seal retaining block needs to be removed.
This engine, for all its problems, doesnt leak at the rear seal.
Whats the consensus in removing the seal retainer to replace #5 main, and possibly messing the rear seal fitting up.
Remember, the engine is still in the car and access is tight.

Dunc, when you have replaced these in the past, have you fitted a neoprene 1/2 and 1/2 seal or the older rope type seal?
How do you fit the neoprene type? Do you sort of 'walk' the seal in?

Appreciate any pointers you/folks can give. The last thing I need now is to get to a point where I have to remove the motor to get to the rear seal.

As I mentioned, I plan on a full car rebuild (inc. bodywork) sometime soon-ish so Im really cautious.

Is it perhaps best to leave #5 and the rear seal until I have the engine on a stand and can replace it properly having good access ?

Cheers
Andrew

If you know you are going to remove the mtr in the nr future and you have no leaks now then leave that no5 alone,

I use the rubber type seal that comes in a felpro kit and yes gently push the old seal around the crank with a punch or similar and put the new in the same way little bit of lube on the lip

Thanks Duncan,

I think I`ll leave well alone and sort it out when the engine is out.

Fitting a new oil pump tomorrow, and buttoning it all back up. Fingers crossed it all starts and runs well.

if the cam bearings are flaking away ,,,,,,,sort of a waste of time