Pinch on main bearings

Mike Allfrey · Post by **Mike Allfrey** » Tue Mar 06, 2007 10:00 pm

Dear Keith,

I will place in the post to you today a CD with 64 megabytes of Technical Notes. This is not a service manual as such, but is mostly my findings from experience.

When I build an engine I take the crankcase set (less all studs), cylinder liners, crankshaft, camshaft, cylinder heads and rocker gear to my local engine repair shop. I am extremely fortunate in having a shop that I can really trust. They have recently machined a crankcase for a vintage Bentley from a blank casting. Another example, they have rebuilt a GP Alta engine and get into all manner of interesting stuff. Their bread and butter work is Ford and GM work, and it is having Ford's authority to carry out warranty work on certain components, that they have the right up to date machine tools to work on my Jowett stuff. All Javelin and Jupiter information is now loaded into their computer - so setting up machine tools is an easy matter -- now!

Basically, the procedure with a crankcase is to accurately measure the main bearing tunnel bore in the three supports. If there is distortion here, it is noted and then the same measurements are taken at the camshaft tunnel bore. This determines how much, if necessary, needs to be skimmed off the joint faces to reclaim the bores. Usually 0.003". In severe cases, the dowels at front and rear are re-aligned. They have also checked the flywheel housing rear main seal bore for truth.

They are reasonably expensive, but do the job in an utterly professional manner - and you get it back when they say it will be ready. I am indeed most fortunate!

For my Jupiter the crankshaft, camshaft and cylinder liners were all matched and assembly by myself was a breeze. However, the cost was such that the vast majority of Jowett owners would blanche and loose interest. I regard such work and cost as an investment for reliability and enjoyment of Jupiter ownership. I am indeed extremely fortunate that Sue is very supportive and lets me do as I wish with respect to our Jupiter - it is a very fortunate motor car!

Regards,

Mike A.

Robin Fairservice · Post by **Robin Fairservice** » Tue Mar 27, 2007 5:10 pm

For Keith; did you solve you low oil pressure, because I have the same problem and would like some clues?

Robin Fairservice · Post by **Robin Fairservice** » Wed Mar 28, 2007 11:06 pm

I started the car up and the pressure rose to 55 psi and stayed still. So from what you say I may have a stuck relief valve. I believe that one could access this if the sump is removed, then how can this problem be fixed?

TedAllen · Post by **TedAllen** » Wed Mar 28, 2007 11:39 pm

Robin, You are so lucky that the pressure let go at 55 psi.
A few years ago I rebuilt an engine and changed the pump for one I had in stock. Starting up, she ran very well until I saw the oil pressure was off the clock. I shut down and went round the front where I saw, to my horror, new oil dripping from everypart of the engine and sprayed everywhere under the bonnet including a widening pool under the car.
A completely stuck pressure valve was the cause. The pressure had been so high that the oil filter canister had been forced away from the rear timing cover against the retaining bolt causing a massive explosion of pressurised oil. The filter canister was damaged beyond repair, being pushed in at the bolt head end. The original pump cured the problem together with a new canister. Has this happened to anyone else ?

Ted

Robin Fairservice · Post by **Robin Fairservice** » Thu Mar 29, 2007 9:24 pm

Thanks for all of those ideas. The engine was rebuilt last year with new bearings and runs nicely. No temperature problems and it has only done about 100 miles. The low pressure when hot has been there since it went back into service. It has hydraulic tappets and they seem to funcion OK, so there must be enough pressure for them. The gauge shows about 10 psi hot.

I have been colecting parts for a spare engine which will be put together this summer (after a visit to the UK Jowett Rally). Neil Moore in NZ has rebuilt the oilpump for that engine with larger piping.

Mike Allfrey · Post by **Mike Allfrey** » Sat Mar 31, 2007 9:41 pm

Dear Robin,

On my engines I have been using a 2 mm aluminium plate and suitable 'O' ring in place of the gasket at the top of the oil delivery pipe. This has always worked well.

I have found that all of Neil Moore's modified oil delivery pipes are an excellent fit into place on the engine.

Good luck with the trouble shooting!

Mike Allfrey.

Robin Fairservice · Post by **Robin Fairservice** » Sun Apr 01, 2007 1:37 am

Neil Moore has modified the Oil Pump for my spare engine and provided the aluminum plate, so hopefully some of these issues will be resolved in that engine. I now have to decide if I will take the sump off the engine that is in the car before we go away on holiday.

Mike Allfrey · Post by **Mike Allfrey** » Sun Apr 01, 2007 10:17 pm

G'dday From The South,

To date, I have not used supportive hollow dowels for 'O' rings in my engines. Provided the 'O' ring is fully seated on both faces, there is no real need. Oil pressure will keep the ring backed against the aluminium plate, a theory that seems to work. That is why, when converting the rear timing cover gasket, I 'relocate the oil drillings in the crankcase to match those in the rear timing cover. Quite involved, but it works.

In addition, I have no problems with the relief valve exhausting to sump. The oil cooler is between the oil pump and the various oil paths within the engine. The main concern is that oil is returned to sump via a pipe below the oil level - or to the suction side of the oil pump as with the Series III oil pump set up.

Back in 1963, my Jupiter ran quite happily with the oil pressure gauge indicator needle just lifted off the stop at 60 mph. Ignorance was bliss in my unknowing youth and motoring enthusiasm. After a crude overhaul, the engine suffered total loss of oil twice - once with a holed sump and then when a rocker cover nut came off on a long night drive - without damage to bearings and other components.

Robin, I have a feeling that your loss of pressure could be due to a relief valve problem. I have had a Javelin engine on my test rig that suffered a broken rocker feed pipe at the head stud banjo, without a flicker at the oil pressure gauge. the rocker cover soon filled with oil though!

That means that, if there should be a leak at the oil delivery pipe, with good pressure when cold, then the pressure should not drop off so much when hot. Maybe I am wrong.

What is your oil pressure when cold - and how cold? In British winters my Jupiter, after its good overhaul, indicated 100 psi. That made me wonder about the poor Bourdon tube in the gauge though!

An aside on relief valves - on Ford tractors they can stick in the home position and then the weakest point is the low oil pressure switch. The internals have been known to 'let go' and allow the pent up oil to squirt 15 feet! Here in OZ we have a saying - a good Jowett squirts its oil 18 feet!

I will think about it some more.

Regards,

Mike Allfrey.

Robin Fairservice · Post by **Robin Fairservice** » Sun Apr 01, 2007 11:36 pm

I haven't tried at -25 C, but the car is in a garage that rarely dips below 0 C. Last week we had about +5 C outside and it started easily. I have an electric fuel pump and electronic ignition. The latter makes a lot of difference for starting. The "cold" oil pressure is 55 psi.

Mike Allfrey · Post by **Mike Allfrey** » Mon Apr 02, 2007 10:22 am

Dear Pat,

I run my oil pumps on a test rig prior to installing them into an engine. The pump is run, dead headed to an oil pressure gauge. At an indicated 75 psi, and running at 2,000 pump rpm (4,000 engine rpm), and run for several minutes, no appreciable heat is generated. The rig holds 5 litres of oil. It is interesting to observe just how much oil is escaping at the timing chain jet and the skew gear jet! All this while holding 75 psi..

Robin,

Does your engine have a white metal rear main bearing, and if so, how long has it been in place?

Perhaps you could give me a rundown on what was done to the engine at overhaul time? I am a bit worried about the hydraulic tappets though. My only experience with them has been in locally built Ford Falcons where it seemed that the only lifter to give trouble was number five exhaust! I have used a bottled product that is supposed to free-up lazy hydraulic lifters - not sure if it is Nulon or Wynns though.

I will keep on thinking!

Regards,

Mike Allfrey.

Robin Fairservice · Post by **Robin Fairservice** » Mon Apr 02, 2007 4:52 pm

When the engine was taken apart it was discovered that there was a three thou out of alignment of the crankcase. It was line bored and the white metal main bearings were re-metalled. WHen the spare engine is put together I will swap the engines, but this won't happen for 2 or 3 months as we are going to be away for 6 weeks, and Ihaven't started on the spare engine. Ihave also wondeed about the rear main, but with a stethoscope cannot hear any odd noises.

Now that I belong to the NZ club, I have found that they can supply full sets of gaskets seals etc. at a reasonable price, I will replace them all, and get the oil pump overhauled by Neil Moore. They wil also sell direct to me, not like JCS!

Mike Allfrey · Post by **Mike Allfrey** » Mon Apr 02, 2007 9:39 pm

Dear Robin,

I will post you a compact disc with a heap of service information on it. Please take the time to read carefully the information about the Jowett engine.

I note that you say that the main bearing tunnel was rebored. Were the joint faces skimmed prior to the boring operation? What about the camshaft tunnel?

I sincerely hope that, at crankcase assembly time, no sealant was applied at the main bearing support faces. These must be a metal to metal joint! Modern sealants 'grow' during curing and, at this joint, can cause bearing shell crush to be completely lost.

I am not altogether impressed with re-metalling white-metal shells. It would be far better to use Perkins bearings with separate thrusts at the rear, as supplied by New Zealand.

However, all that said, you say that a stethoscope reveals no untoward noise, so the mains appear to be OK. My main concern is that the white-metal may have dislodged or been eaten away by combustion residue acids.

Are you using a good quality multigrade oil?

Once I have your address, the disc will be on its way.

Regards,

Mike Allfrey

Post by **Forumadmin** » Mon Apr 02, 2007 10:37 pm

Note Robin has access to all on the CD on JowettGallery.
TOPIC

Keith Clements · Post by **Keith Clements** » Tue Apr 03, 2007 6:00 pm

I am intrigued to know how you run the engine with the sump off, manage to get oil into the oil pump and not get covered with the stuff when watching for the gusher! Am I missing a trick?

Mike Allfrey · Post by **Mike Allfrey** » Wed Apr 04, 2007 1:25 am

G'dday From The Clear Blue Skies Of The South,

Keith Clements mentions accessing the material at the Gallery.

I have tried several times to get into the gallery, but it does not like my name or password - oh dear!

I think that, were Horace Grimley still alive, he would be able to describe how to run a Jowett engine minus sump!

I remember the good old days when the Yanks used to establish advertiseable horsepower claims. Engines were tested minus water pump, fan, distributor, dynamo, power steering pump and engine oil pump. Of course all of these were power consuming devices!

A Jowett could easily be run without its engine oil sump by attaching a hose to a spare suction pipe, placing the hose in a 200 litre container full of clean engine oil and having that container at about oil pump level. Ideally the car should be on a hoist and the observer should be prepared for a fair dinkum deluge with a suitable catching container and appropriate clothing!

What a subject for a garage day!!

I'll get out of your way now,

Mike Allfrey.