Tightening Valve cover: oil leak

[asifallasleep]

Had valve job done and replaced valve cover gasket. Drove the car and discovered oil is leaking from under the gasket so i tighten the valve cover bolts. Drive car, smell oil, check again and oil still leaking. I figure i don't have the bolts tight enough. The bolts appear to have loosened, i'm guessing from the metal expanding. This scenario has repeated itself 4 times with me lastly adding more red silicone under the gasket. Still leaks. What gives? I'm trying not to tighten the bolts too tight as i've read doing so can crack the valve cover. How do I know know when tight is too tight. Also, is it normal for the bolts to loosen a bit from the heat expanding the metal? Thanks.

[89e30]

They really dont need to be too tight. Im guessing the gasket is bad.

[asifallasleep]

Brand new gasket!!

[napa02]

Is your cover warped?

[Chamonix72]

Was the head machined, and if so, was the upper timing cover machined to match?

[SteveJ]

Can you tell where the leak is from? If not, let it cool, put on your safety glasses, and spray it down with some brakleen or suitable cleaner.

Leaks above the #4 spark plug are usually from the valve cover gasket. Leaks above #1 are sometimes the gap withe the front timing cover and the valve cover. The exhaust studs can also leak by and drip oil right on the exhaust header. Clean out the oil, pull the exhaust studs, re-install with some blue loctite (not heavy duty red) to seal the threads.

The distributor mount can also leak. Several bolts and it's own mounting gasket. Further up, the o-ring on the distributor shaft can ooze a bit if it's that loose. Not usual, due to gravity.

Any leak up front will travel both down and backwards due to the engine fan. Also, any oil on the header will take a while to burn off, so it may smoke for a while. Clean it all up and try to see where it is coming from.

[wess02]

do you have wave washers under the nuts? could be sumthing very easily over looked.

[craaaazzy]

Can you tell where the leak is from? If not, let it cool, put on your safety glasses, and spray it down with some brakleen or suitable cleaner.

Leaks above the #4 spark plug are usually from the valve cover gasket. Leaks above #1 are sometimes the gap withe the front timing cover and the valve cover. The exhaust studs can also leak by and drip oil right on the exhaust header. Clean out the oil, pull the exhaust studs, re-install with some blue loctite (not heavy duty red) to seal the threads.

The distributor mount can also leak. Several bolts and it's own mounting gasket. Further up, the o-ring on the distributor shaft can ooze a bit if it's that loose. Not usual, due to gravity.

Any leak up front will travel both down and backwards due to the engine fan. Also, any oil on the header will take a while to burn off, so it may smoke for a while. Clean it all up and try to see where it is coming from.

i've had luck spraying foot powder on clean surfaces to track down oil leaks.

[ray_]

I've read that for some applications the valve cover gasket is thinner that the original spec, leading to studs that are essentially too long to allow the cap nuts to torque the cover properly. Thicker washers may be the solution.

GL,

Ray

[Napes]

You're correct to not over-tighten the acorn nuts on the valve cover. Spec is 8 lb/ft, which is not a whole lot.

Bob Napier

[Guest Anonymous]

remove valve cover. remove gasket. inspect each mating surface for irregular level. Sometimes the level of the head is different from the level of the front timing cover (as mentioned). If you find a low spots, cut cork gasket material to fill the gap, mount with gasket adhesive. Then place new gasket over built-up section. Clean cover surface and mate. Torque bolts at spec. from book. They're small nuts and probably don't need more than 8 ft/lb. Dont deform the cover metal or you'll create a leak.

[Guest Anonymous]

Had valve job done and replaced valve cover gasket. Drove the car and discovered oil is leaking from under the gasket so i tighten the valve cover bolts. Drive car, smell oil, check again and oil still leaking. I figure i don't have the bolts tight enough. The bolts appear to have loosened, i'm guessing from the metal expanding. This scenario has repeated itself 4 times with me lastly adding more red silicone under the gasket. Still leaks. What gives? I'm trying not to tighten the bolts too tight as i've read doing so can crack the valve cover. How do I know know when tight is too tight. Also, is it normal for the bolts to loosen a bit from the heat expanding the metal? Thanks.

Do you own a manual? Have you read it? Or even the archives? Do you own a torque wrench, even an inexpensive beam type?

When you ask about tightening a fastener, most manuals give a specific torque setting. From memory, the valve cover nuts require 7-8 lb/ft. None of the manuals I have read discuss using any sealant (silicone or otherwise) on the valve cover or the valve cover gasket. Sealant has been mentioned where the front timing case cover meets the head, but given your description, it sounds like you have slathered the stuff around. I would wager that a search of the archives would reveal that conventional wisdom is that the valve cover gasket works best "DRY." If treated "gingerly" the gasket can last for years. Using sealant may work, but it becomes counter productive if you routinely examine the valve train. The old sealant can prevent the new sealant from properly functioning.

While on the subject, why do you persist on saying you performed a valve job? Did you pull the head and lap the valves? Or did you merely check the valve lash and adjust the valves?

hth

[Guest Anonymous]

Did the shop surface the head when they did the valves? If they did the front cam chain cover may be too high and not allow the valve cover to properly seat onto the head.

Have fun

[///mChris]

resurfacing a valve cover is a cheap and easy way to rule out the cover.

[tzak12]

The bolts appear to have loosened, i'm guessing from the metal expanding.

Use thread lock