Can't find an oil leak

[bighealeysource]

Hey y'all,
Been asking a lot of questions lately as finally have got
my BN6 99% finished and back on the road - ooh rah !!!
Of course now I have operating issues/questions. I started
the link about the operating temp on this rebuilt engine
and looks like it will run fine at 200 degrees, so still
high but know my timing is not quite right yet.

My oil leak question - had it out today for about 40 minutes,
primarily at 50-55 mph and ran like a champ. When I got to
my first stop after 20 minutes - noticed the oil pressure
dropped down to 20 or less at idle. Stopped it, checked oil
and it was okay so went in the store for about 15 minutes
came back out and started immediately but oil pressure at
idle was still about 20 or less. Proceeded cautiously and
pressure went back up to 40 or so and stayed there. Had
been running 50-60 earlier. Got back in 20 minutes, again
ran great at speed and parked it. Checked the oil again
and still okay.

Looked under the car and I was marking my territory from
fresh oil that had obviously come from somewhere - engine or
tanny - and had been sprayed onto the frame rails from about
the rear bulkhead back. Probably about a few tablespoons worth. I immediately checked everything again. I have had
a few drops - maybe a silver dollars worth from the trans/OD
drain plug before - and again you could see where oil was
getting ready to drip again. Checked the trans oil level and
still okay but maybe this is where it is coming from ?
Figure when the oil gets hot, thins down so tends to leak
easier and this was the first time it has been driven this
much. Trans shifted great entire time as it too has been
rebuilt. I'm going to make sure this plug is tight but does
anyone have any other thoughts ? No oil on top end of engine
at all, and sump clean too so this oil being thrown back
to the rear was probably not coming from the engine.

Any ideas and thoughts appreciated.

Thanks,
Mike

 

[Richard Dickinson]

I had a bad oil leak on the first start up of a newly rebuilt BT7 engine. Oil appeared to be coming out of the rear of the engine. Turned to be leaking at the back of the valve cover box and running down the back of the engine.

 

[Healey 100]

FYI, your oil pressure sounds fine to me. For a hot engine at idle, 20psi should be fine.

Get at least 1000 miles on this engine before you get too concerned about it overheating. It sounds like it's running a bit hot, but there is lots of friction and heat generated in a freshly rebuilt engine. Sure, make sure the timing is not retarded, but loosening up the engine is important. Try to get some road miles on it, take it out on the open highway at night. Until you get it broken in, just avoid slow traffic on hot days or parades.

This is a Healey, it is probably going to leak some oil. I agree with the post about checking the valve cover gasket, these are hard to get centered.

Most of all, have fun with your Healey!

Bill.

 

[BUNDYRUM]

Hello bighealeysource,

So the age old story of the Healey oil leak question arises again, but don't worry there are always plenty of answers here.

I haven't read all your previous questions but to answer the above I'll give it my best shot.

Re-set the ignition timing to as close as you can get it, regardless of how much time it takes. I personally would make this my first item to be dealt with. On a new engine you don't want it to run too hot but because the clearances are all tight it will run somewhat hotter than when it will after being "run in". 200 sounds about right but I would keep my eye on it as you are already.

Do you have a new thermostat and do you know if it is operating as it should?. Even new ones can give trouble.

Have you had anything done to the radiator?, cleaned out or re-cored. They do tend to get clogged with rust from inside the engine block over time.

With your oil pressure issue you may be having trouble with the oil pressure relief valve. Did you install a new one and or have the valve seating face in the engine block re-cut. It may not be seating properly.

Did you install a new spring in behind the oil pressure relief valve. In the "Haynes" manual it gives a dimension of 2.562" (2 9/16ths")and 13 coils for the BN4/6 engine. The 3000 engine is 2.687" (2 11/16ths") but this would have the effect of increasing the pressure rather than decreasing it. If your spring is too short you can install a washer or two between the end of the spring and the inside of the valve itself. I would hope a new engine would have a higher oil pressure than an old engine because all your clearances are close.

Yes I agree that oil leaking out of the rear of the valve cover is a common problem but you will see it when you shine a light down there.

Did you install an aftermarket rear main seal kit?. Sometimes this will leak initially till the seal itself is properly seated, then the leak stops.

Gearboxes & O/D's are a common area for oil leaks depending what type of gaskets/sealer was used in the rebuild. You will get many answers on what should be used.

One of the most common areas of leaks in the O/D is the operating valve cross shaft. it is the shaft that connects the solenoid to the operating lever on the opposite side of the O/D case. That is in the front section of the O/D unit. Of course there are all the joints between the O/D cases, adaptor plate, & gearbox. The O/D will leak oil whilst the car is sitting doing nothing else. Check all the nuts/bolts securing everything together.

I'll bet it's nice with the gearbox shifting great, always a good feeling.

Best regards,

bundyrum.