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  • January 17, 2021, 10:42:11 AM

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Author Topic: Oil leak pan or valve cover???  (Read 547 times)

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Offline charlie D

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Oil leak pan or valve cover???
« on: November 02, 2020, 04:41:24 PM »
Been sorting out my Eagle and things are going pretty well. Mostly doing local 20-30 minute runs with some on the highway. Last week took it for about 40 minutes on highway, running 60-70. All fine until I pulled off and went to park. Smoke started coming from under the hood. I have had a 'weeping' of oil at the valve cover(still plastic) and figured some had made its way to the exhaust manifold. BUT when I went to open the hood there was a puddle of oil under the front of the car and I could see drops following me to my parking spot. There was oil all over the front to the engine, on the belts, fan, etc. I got a tow home, cleaned up the mess, started it and let it idle for 10-15 minutes and started looking for leaks. Still just see some weeping at the valve cover, and there is some at the front of the oil pan. SOOO, I'm thinking maybe the oil return passages are gunked up and the oil just filled up under the valve cover so the 'weep' became a flow? Thinking the valve cover and maybe converting to an aluminum one is the simplest approach. The pan looks like more than I want to tackle working without a lift. Any suggestions welcome!
Charlie D

Offline rmick

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Re: Oil leak pan or valve cover???
« Reply #1 on: November 02, 2020, 05:38:19 PM »
Could also be a front timing cover seal
72 Javelin AMX
72 Javelin SST
72 Gremlin with 4.0
81 SX 4

Offline charlie D

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Re: Oil leak pan or valve cover???
« Reply #2 on: November 12, 2020, 04:35:22 PM »
OK so I have an aluminum valve cover and associated parts to install it to solve(hopefully) the weeping/leaking plastic valve cover. As I said in my previous post I was really hoping to see some gunked up mess when I took the valve cover off. No such thing. Actually very clean, oil is dirty with only about 300 miles on it, but no signs of blockage to the oil return passages on top. The previous owner may have replaced the plastic valve cover as it looks pristine on the underside, not at all what I am accustomed to seeing. So good news is clean on top, bad news is not sure what sparked the leak that got me on this journey. Also, did not lose much oil with the leak, not enough to even show up on the dipstick. Weird.

Online mudkicker715

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Re: Oil leak pan or valve cover???
« Reply #3 on: November 12, 2020, 09:40:23 PM »
I found away to use valve cover saddle clamps back in the day to help clamp
 a longer area. I cannot find a pic of that
use your imagination.

also the pvc needs unrestricted flow to carb.  so take any check valve that might be present out. breather thing, if you have one ditch it.  basically your putting vac on your manifold. so make sure oil fil plug seals. that has worked for me. no significant oil consumption going that route. there was a thing in AMC days to pull the check valve.

just my experience.  even with fresh rebuilds.



Manitowoc WI

Offline Canoe

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Re: Oil leak pan or valve cover???
« Reply #4 on: November 14, 2020, 12:50:37 PM »
... also the pvc needs unrestricted flow to carb.  so take any check valve that might be present out. breather thing, if you have one ditch it.  basically your putting vac on your manifold. so make sure oil fil plug seals. that has worked for me. ...
That's fine as long as nothing ever fails. We need to look at PVC venting further. 

The purpose of the PVC is to provide a venting of positive air pressure when there's blow-by past the pistons (and in an emissions acceptable manner).
- You have to provide a way of getting rid of that positive pressure or it will eventually blow something, like the valve cover gasket.
- It doesn't require a huge amount of blow-by; a tiny bit of blow-by can build up pressure too.

The PVC valve has two functions: to close when the carb isn't pulling when the engine is off (to contain emissions), and to limit the amount of airflow when vacuum pulls it open so it doesn't act as a vacuum leak.
- Unrestricted pull (vacuum leak) can mess with the available vacuum pressures, hence with everything running off them.
- A working PVC valve is the superior way of handing it, but they can fail - and you usually won't know until there's a problem.
- Another way of handling it is to replace the PVC valve with the fitting (plastic elbow #47057) that is always open (no valve to fail closed) but with a smaller hole for the required airflow limiting.
- In some jurisdictions, or since they already have the failed PVC valve, people have drilled out the PVC valve with a smaller bit, so it appears in place, but is always open, yet still provides the required airflow limiting.

Deleting the PVC breather, the sealed oil filler and having unlimited pull by the carb, is relying upon limiting that vacuum pull by all of those remaining sealed, so it doesn't become a vacuum leak. And if there is a big blow-by event, there's nothing to handle the increased pressure - something will have to give/blow. Good enough - as long as nothing starts to fail.

The Eagle PVC setup allows for fouled air emissions to go to the carb and be burnt off, and higher pressures can get out through the breather, buying you time to detect that something has gone wrong. The problem with the Eagle PVC setup, is it doesn't adequately manage oil shooting up the breather line or up the venting line, nor the high incidence of a fouled PVC valve sticking closed or having a too restricted airflow. Various methods have been tried/developed to catch and drain-back any oil that goes up where it's not wanted. Sometimes that's a small chamber for oil to gather and flow-back (and sometimes with a metal mesh to catch oil droplets), sometimes a length of hose running upwards for a length is enough. search...

So you'll have to do some thinking about how the whole combination of components will work as a system that can/will vent positive pressure (both when it's low and when it's high), keep the oil where it belongs, and limits airflow to the carb and filters particles out of the breather air going in (contaminate engine oil). And how those will work as a system when components fail: consequences and how will you detect that failures are starting to happen.

Online mudkicker715

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Re: Oil leak pan or valve cover???
« Reply #5 on: November 14, 2020, 05:26:06 PM »
better explained on what I was saying on the second post here

http://forums.amceaglesden.com/index.php?topic=46621.0



Manitowoc WI

Offline charlie D

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Re: Oil leak pan or valve cover???
« Reply #6 on: December 16, 2020, 10:42:36 AM »
Simple valve cover has turned into a rabbit hole, mostly of my own making. I am sure many of you have gone down a similar road of " why not do this since I am already here..." Well, I decided to give the plastic valve cover one more shot. I used a method that I used successfully  in the past on British cars and shelby GT500 to seal leaky valve covers. I did a double cork gasket and used Hylomar as a sealant. Got turned onto Hylomar in British forums and have found it very useful for many gasket applications. Anyway, after the usual struggle to get the valve cover in place, I torqued everything down to the 28 in-lbs spec, started the engine and it still leaked. So I took it off, got the aluminum valve cover in place, after drilling and tapping the head for the new bolts, torqued it down to Omix specs, 55 in-lbs, started the engine and it weeps, barely, but it weeps. It is near the front by the idler pulley bracket for the A/C compressor. I did machine down that bracket for clearance for the aluminum valve cover so it is not the issue. I suspect reattaching it with a little RTV along that area might solve the issue. Otherwise, I usually only tack valve cover gasket in place with the Hylomar. Suggestions welcome.

 Now for the rabbit hole. Since I was already there and everything is pretty tight I did some "may as well" work. I drained the coolant from the radiator to install fresh when done with the hoses. Installed a replacement upper radiator hose, water pump to manifold hose, and manifold to heater hose. When I started the engine, I had coolant pouring out under the car near the rear of the engine. None of the hoses I replaced showed any sign of leaking. I vowed not to do work under this car, but here we go again. Any idea what I should be looking for under there? This came as a complete surprise. Part of the journey working on old cars, should help keep the brain sharp!
Charlie D

Online mudkicker715

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Re: Oil leak pan or valve cover???
« Reply #7 on: December 16, 2020, 01:51:31 PM »
just a guess, but thermostat housing. did you replace the t stat?



Manitowoc WI

Offline MIPS

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Re: Oil leak pan or valve cover???
« Reply #8 on: December 16, 2020, 05:11:13 PM »
The only points the engine can leak coolant near the back of the engine is from the manifold-to-heater core line or the temperature sender. Did you burp the system from the sender and forget to screw it back in? ;)

 

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