oil consumption and low pressure

[BobHorvath]

I have a 65 bj8 with oil consumption and low pressure @temp. I have had the rockers re-built and have replaced the by-pass spring and plunger, slight improvement out of each. I can't afford a re-build with this economy and am considering pulling and overhauling the head, droping the pan,pulling the pistons/rods, cleaning up the walls,fitting new rings and replaceing all the bearings. Is this a mistake?

 

[BobHorvath]

I should have added less than 10#s hot at 700RPM & about 1qt/100mi

 

[Keoke]

Hi How low is the oil pressure and what weight oil do you use?---Keoke

[OK, What is the pressure at speed say 3500 RPM Hot?

 

[BobHorvath]

10lb@700 hot 20W50

 

[Keoke]

10lb@700 hot 20W50

What is the oil pressure at speed say 3500 RPM hot? and have you checked the compression of all the cylinders--Keoke

 

[Keoke]

I have a 65 bj8 with oil consumption and low pressure @temp. I have had the rockers re-built and have replaced the by-pass spring and plunger, slight improvement out of each. I can't afford a re-build with this economy and am considering pulling and overhauling the head, droping the pan,pulling the pistons/rods, cleaning up the walls,fitting new rings and replaceing all the bearings. Is this a mistake?

In my opinion yes it is. For example: "cleaning up the walls" may dictate that over-sized pistons are required. Similarly, the crankshaft may require machining requiring that the rods and big end bearings be replaced with over sized ones---Keoke.

 

[BobHorvath]

Pressure starts out @ 60#s through out the RPM range and drops to 20#s on a hot day. If I encounter a the crank needing machine work I will remove the engine and do it correctly. Can I go say .005 over on a wall clean up? Can the stock pistons handel a small over size ring?
WELCOME BACK Keoke

 

[Randy Forbes]

Never tried putting oversize rings on a std. bore pistom before, but years ago (like 1977?) I took apart an MGB engine that had the piston skirts knurled to "add" some material to them. It's possible that they had an oversize ring.

It was interesting to note that the engine had three (3) completely different type/brands of pistons in it, and (only) one (1) of which was a short-skirt design. NO WONDER the engine didn't rev; couldn't have been anywhere near balanced!

 

[Keoke]

Pressure starts out @ 60#s through out the RPM range and drops to 20#s on a hot day.

Boy! not good but you can coast down to ["Tahoe Healeys's House for a cool one}--Just Kiddin . However it will probably last until you do a proper rebuild.

If I encounter a the crank needing machine work I will remove the engine and do it correctly.
--OK. Then I think you will be doing it correctly anyway,---

Can I go say .005 over on a wall clean up?
---Sure if that would clean it up.

Can the stock pistons Handel a small over size ring?
--Yes if the ring groves are good.

WELCOME BACK Keoke

P.S See what Randy said you just do not know what you are going to find until you get nside.--Keoke

 

[Patrick67BJ8]

Be sure to check the oil relief valve spring "end" for the correct one. There are diffeent types(at least two). This was discussed in late 2008 posts.
You can also add washers to this unit to increase the oil pressure.

When I bought my Healey in 1972 it had good oil pressure until I rebuilt the rockershaft. Upon close examination of the oil feed tube on the pedestal I found what appeared to be an indentation done with a hammer and regular scewdriver. This slowed the oil flow to the shaft and kept it from "squirting oil". I'm sure it also raised the oil pressure too. This might be a good "temp" fix???
Patrick

 

[TimK]

Are you blowing blue smoke? Were the rocker arms re-bushed? Have you looked at the amount of oil coming from the rockers (should only be dribble). You could try honing the cylinders if they are glazed and blowing smoke. This can be done with the engine in the car.

 

[BobHorvath]

I am blowing blue smoke. The rockers were done here in norcal by a very rep. shop. Amount of oil comming out of the rockers is less than when I sent them in. I am trying for a hone while the engine is still in the car. Possibly bore out as well.

 

[twas_brillig]

I started a thread in Dec. (?) with the same issue; turns out replacing the cone and spring for the overpressure solved it for me. Have a check in the old threads, as it included the length of the 'old' spring (I had two: one in the engine plus one of the same length in a bag, source unknown)plus the 'new' one (which, I think, was a quarter inch longer) and compare the lengths with your new and your old.
Nock's book advises pulling the valve cover to check for oil leaks from the rockers; I'd initially peered through the filler cap and then pulled the cover, and my rockers were okay. We have a BJ7 with about 65 000 miles on it, but diddly squat for miles since the early 70s. This year though!

Doug

 

[Healey 100]

Your oil pressure doesn't sound all that bad to me. I have been driving my 100 for 35 years with similar oil pressure, 10 psi hot idling under 1000 rpm. Maybe 25-35psi hot at 2 to 3K RPM.

I would not waste money with half fixes on this car. Just keep adding oil, enjoy your Healey and save your money to do the job right in the future. Doing it right means at the very least rebored cylinders, new pistons, rings, reground crank with bearings set to the proper clearances, and check or rebuild oil pump. This will eliminate your oil consumption and increase oil pressure.

Putting new rings on the existing bores is a lot of work and may or may not fix the problem. Your low oil pressure is likely due to excessive clearance on the main bearings. This can also lead to severe oil leaks out the rear of the engine.

Bill S
Albuquerque

 

[BobHorvath]

thanks for all the input. What about oil consumption through the heads/valve guides?

 

[glemon]

When Road and Track did their used car classic on Big Healeys they said something like the motors rarely break, they just gradually increase tolerences and consume more and more oil.

At the point where you are talking about boring the cylinders with enginge in place I think you are talking about enough work that you might as well pull the motor, once you have the head off there is not that much more to do to pull the motor.

That being said I think you have a lot of options, none are "right" or "wrong"

Just what fits your time and resurces the best.

Of course if time and money were no object a complete rebuild with the best possible parts is the best option.

You might get a few more pounds of pressure and piece of mind if you pull the pan and put on new rod bearings and maybe refresh the oil pump (you can close tolerances with some careful sanding of the base plate and housing so the clearances are tighter). This may get you an additional 5-10 pounds of pressure.

Penrite makes a 20w-60 oil, I haven't tried it but some have said you get a few more pounds of pressure using it.

Good luck, I agree that you can drive and enjoy it as is. As far as the additional work, I don't know that I would pay somone to pull the pan, but if you have the time and inclination might be worth a try.

 

[Healey 100]

When my Healey was rebuilt the shop installed modern valve seals and put bronze inserts in the guides. I can't really comment on how much this reduced oil consumption. My car did not smoke significantly before rebuild, but it leaked a lot through the rear seal. She used about 1 quart per 250 miles before rebuild.

Obviously, when the engine goes to the machine shop, it is important to correct all the sources you know of for wear and oil consumption. I would rework the head and valves while the short block is being done, the added cost is minimal at that point.

 

[TimK]

Burning oil and low oil pressure seem to indicate a worn out engine. Burning oil and low oil pressure could be caused by worn out rocker shaft (deep wear on the bottom surface of the shaft at each rocker pedestal). But since you have had the rocker shaft replaced when you had the rockers rebuilt (I hope), that probably isn't the cause. I would think you have a worn out engine that needs new rings and bearings. I am not familiar with Healey push rod sealing, but on an MGB, there are rubber seals that can go bad and cause blow-by. I tend to agree with others that a thorough overhaul at some convenient time in the future is the best approach.

 

[anthony7777]

doing a total rebuild id think you might want to check the clearances of the oil pump as well couldnt hurt i.m.h.o