• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Engine Oil Leak After Long Drive

Share this page

Zitch

Zitch

Jedi Hopeful
Country flag
Offline
After a long 60+ mile run local roads and highway my BT7's engine is blowing oil over the top of the hood (bonnet).

And the rear air filter was full of oil.

I was at first thinking it was the valve cover / oil cap leaking but... with a little research it maybe more.

- ring blow by

- worn rockers

Thoughts??

Pictures/details:

Hood:

o6pUerx.jpg



Rear air filter:

Is this a lot?

18I2PpQ.jpg


UGH!


Dry cylinder compression test: no oil squirted in the plug hole... hmm...

If im reading these correctly:

1 - 115
2- 110
3- 108
4- 90
5 - 112
6 -110



I'll squirt some oil in the holes and try again.. see if its the valves or rings.
 
Yes, #4 looks low.

How's your oil pressure?

If you run it and take to oil filler cap off, you can see if oil is really pouring out of the rocker arms. If so, it will end up in the breather and rear air filter. It should drip out each rocker arm.
 
Inspect flexible oil pressure hose from engine block to solid pipe union for signs of leaking oil. The flex hose can degrade internally over time allowing pressurized oil to push out through the reinforce braiding. Good luck.
 
Do what John says. I suspect your rocker arm bushings are worn out. That allows way too much oil to squirt out. It then gets kicked up into the "T" on top of the valve cover and then gets sucked into the rear carb air filter.
 
Very similar thing happened to me. Turned out to be the valve cover gasket. Messy but fairly easy fix. I replaced the old gasket with a silicon gasket and no leaks.
 
A leaking valve cover gasket does not put oil in your rear air filter. There should be NO OIL in your air filter. You have worn rocker arm bushings.
 
Regarding my valve cover gasket leak, although the engine bay was covered in oil, neither oil filter was inundated with oil.
 
Oops...I mean neither air filter was inundated with oil. It's an old brain here. Hopefully my one and only oil filter is well inundated with oil.
 
In my unhumble opinion your cylinders are obviously getting a lot of oil in them. That is usually from blow-by of the rings and/or valve stem seals.
Also with the hose going from the rear valve cover vent to the carb in the original fashion you will have too much pressure in the crankcase (possibly more so because of ring blow-by). With that hose stuck in the rear air cleaner that rear carb is also ingesting oil into the cylinders. So first thing to do is take the hose off between rear valve cover vent and the rear carb and throw it away. Then install a K&N push on filter on the valve cover vent as seen in the attached picture. This will at least remove the carb from ingesting oil which will help. It will also allow the crankcase to breather better and reduce some of that crankcase pressure. Then by use of a proper compression test and leak down test try to verify whether the cylinders have weak rings or bad valve seals. If it is just valve seals it is not a hard fix and you would at least be able to enjoy driving your car.
( As a side note, realize that the hose and Tee vent arrangement on the Healey as installed by the factory is not a good arrangement. The crankcase usually has too much pressure in it. It is not vented well. That is why they develope oil leaks so easily. That hose to the carb is the only factory original opening to the crankcase and it is not enough. With the K&N filter installed like seen in the pic it helps to reduce pressure in the crankcase. )

DSCF2505.JPG
 
vette said:
...
( As a side note, realize that the hose and Tee vent arrangement on the Healey as installed by the factory is not a good arrangement. The crankcase usually has too much pressure in it. It is not vented well. That is why they develope oil leaks so easily. That hose to the carb is the only factory original opening to the crankcase and it is not enough. With the K&N filter installed like seen in the pic it helps to reduce pressure in the crankcase. )
Click to expand...

Very true. Another solution for excessive crankcase pressure (now if I could only think of a solution for my BN2):
 

Attachments

  • IMG_0418.JPG
    IMG_0418.JPG
    1.3 MB · Views: 125
Bob_Spidell said:
Very true. Another solution for excessive crankcase pressure (now if I could only think of a solution for my BN2):
Click to expand...


Bob any details on what was used? I see the PCV valve.

Are those Standard carb insulators threaded to take brake lines? My carb insulator is not that thick.

And did you use a brake line splitter for the other brass part?
 
Last edited:
I appreciate the environmental consciousness of a PCV valve but your still dumping that crankcase garbage into your cylinders. But at least you wouldnā€™t be spraying it all over the bonnet.
I presume the BN2 has a road draft tube. Of course most cars had road draft tubes up until the 1960s. Best darn vent there ever was. Unless you just take the oil pan off. šŸ˜
 
Zitch said:
Bob any details on what was used? I see the PCV valve.

Are those Standard carb insulators threaded to take brake lines? My carb insulator is not that thick.

And did you use a brake line splitter for the other brass part?
Click to expand...

I started with a 'kit' from BCS put together by Norman Nock; the valve was 'loose;' i.e. not in a box so I don't know the part no. (wish I did). The original kit had the PCV output vented to the spare vacuum port on the manifold; my engine builder who did the most recent overhaul fabricated the current rig. He tapped the 'phenol' heat insulators; actually, it never occurred that he used brake hardware, but that makes sense. I wanted him to install a rear crank seal I'd bought, but he insisted this was a better solution.

I'm somewhat 'environmentally conscious'--I do what I can--but that wasn't the purpose of installing the kit. I used to take a lot of long road trips and would sometimes encounter bad dust storms; I wanted better air filters than the stock 'grasshopper stoppers.' When I pulled the head for rebuild, I was surprised that the back intake ports and cylinders looked not much worse than the front ones. With only a few exceptions--my 2000 Lincoln LS doesn't have a PCV valve, just a passive tube to the throttle body (it's a British engine)--every car built from the early 1970s has PCV. It's considered advantageous overall; including keeping oil cleaner and preventing sludge buildup and, for my Healey reduced oil loss. I did put a catch can inline on my 2019 Mustang GT.
 

Attachments

  • Cyl Head.JPG
    Cyl Head.JPG
    1.1 MB · Views: 120
  • manifold2.JPG
    manifold2.JPG
    136.3 KB · Views: 109
Last edited:
Back
Top