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Hi I took off my spark plugs today to put new ones and found oil down in the threads. Not that much but enough to make it noticible. My valve covers leaked tremendously in the past and I haven't removed the plugs in a year so I'm wondering if it's from the leaky covers. Only 1 and 6 had oil on them
 

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Discussion Starter #3
I think I also stripped the bolt that goes into the 3rd cover in the back by cylinder 6 a while back.. That bolt the connects to the holder for the heater hose. I bought that whole assembly brand new. Dammit
 

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YotaMD.com author
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Hi, Most likely it is leaky valve covers. There are 3 covers. The center cover leaking is the usual culprit that produces oil in the plug holes.
Check # 3 cylinder head cover in the diagram.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=EM&P=32

Luck Semper FI
I think the oil is an indication of a lack of seal in the valve cover gaskets (1 & 2). The third is there to keep other debris out, but it's not a "sealing" gasket, perse. ***Correction the center cover DOES seal around the 4 plugs which hold it on. If the center cover is old that's a likely leak point.

OP, do you have an in-lb torque wrench? Like this: http://www.amazon.com/TEKTON-24320-4-Inch-Torque-20-200-Inch/dp/B00C5ZL2EG

With one of those you can try to check the valve cover bolts and keep them torqued correctly to minimize the oil leaking at the valve covers. Even with careful attention though, those gaskets are a constant pain in my ass...
 

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I do, I torqued them down to 30 in/lbs. when I changed them a couple weeks ago the right one sealed properly but the left did not. It's not a big leak at all. The valve covers used to leak an unbelievable amount prior to the new gaskets I installed. I used to get a quite a few drops on the driveway every time I'd go out and I never thought once to check my plugs so that's been running like that for a long time. So I guess over time a bunch of oil built up. Not to mention the plugs seemed loose when I took them off so they allowed the oil to deep down through the threads and drip onto the piston over night. What a nuisance with these cover gaskets
 

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Hi, have to disagree suprarx7nut. The center cover does seal the plug holes when installed properly. I replaced mine a few months back. The 2 top covers were tight as a drum, yet I was getting oil in the plug holes. I bought a new 3rd cover at the dealer and installed it, no more oil in plug holes. Also when redoing the gaskets on the top 2 covers pay particular attention to packing the areas specified in the manual.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=56
It really makes a difference .
Semper Fi.
 

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I think the oil is an indication of a lack of seal in the valve cover gaskets (1 & 2). The third is there to keep other debris out, but it's not a "sealing" gasket, perse.

OP, do you have an in-lb torque wrench? Like this: http://www.amazon.com/TEKTON-24320-4-Inch-Torque-20-200-Inch/dp/B00C5ZL2EG

With one of those you can try to check the valve cover bolts and keep them torqued correctly to minimize the oil leaking at the valve covers. Even with careful attention though, those gaskets are a constant pain in my ass...
Here is a great read on this problem
http://www.toyota-supra.info/forums/mkiii-faq/7527-got-oil-on-top-of-your-spark-plugs.html
 

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YotaMD.com author
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I do, I torqued them down to 30 in/lbs. when I changed them a couple weeks ago the right one sealed properly but the left did not. It's not a big leak at all. The valve covers used to leak an unbelievable amount prior to the new gaskets I installed. I used to get a quite a few drops on the driveway every time I'd go out and I never thought once to check my plugs so that's been running like that for a long time. So I guess over time a bunch of oil built up. Not to mention the plugs seemed loose when I took them off so they allowed the oil to deep down through the threads and drip onto the piston over night. What a nuisance with these cover gaskets
The spec is 22 in-lbs, FWIW. And yeah... they're one of my biggest pet peeves with the 7M. My 2UZ Land Cruiser engine has 230k original miles and leaks zero oil. Nothing. Anywhere. Yet I'm lucky if the 7M goes 10k without a mess of oil residue somewhere with a lot of care and attention.

Hi, have to disagree suprarx7nut. The center cover does seal the plug holes when installed properly. I replaced mine a few months back. The 2 top covers were tight as a drum, yet I was getting oil in the plug holes. I bought a new 3rd cover at the dealer and installed it, no more oil in plug holes. Also when redoing the gaskets on the top 2 covers pay particular attention to packing the areas specified in the manual.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EM&P=56
It really makes a difference .
Semper Fi.
Bull shit........
The large gallery plugs that hold the center valley cover on, seal on the polymer coating.
By now, that coating is old, and possibly cracked, and will leak oil.
You guys are correct in that it seals the holes around the large plugs that hold it on. I concede that point. I'll edit my post above to avoid confusion for others.

However, the "cover" as it's properly called does not seal anywhere else. It is not a gasket, save those 4 plug areas. If your valve cover gaskets leak a little bit (which is very common in 7Ms) you will get oil accumulating in the center galley and falling into the spark plug holes when you remove spark plugs. The plug wires don't seal perfectly on the holes in the center cover. The snap in mounting points don't seal. Finally, the perimeter of the cover isn't held against the head aside from the ear areas on the 1 and 2 valve covers where the mounting bolts are.

To have a leak free engine you need good seals on all three parts: two valve cover gaskets and the #3 valve cover. I've always had a new center cover (i suppose my current engine's is now 4-5 years old) and new valve cover gaskets with properly applied FIPG. Oil in the center galley is still a constant battle. I have my engine apart for inspection often enough that oil doesn't accumulate to the point of flowing into the spark plug holes, but every time I get in there (every 10k miles or so?) it has oil residue that I have to clean out in the recessed areas surrounding the plug holes.

This all depends on mileage, too. You won't notice much of any leaking if you don't drive it often. Keeping the valve covers from leaking for a few thousand miles at a time is cake. Keeping it leak free for more than 20k miles or something is not easy with a 7M. For a track motor or something it doesn't matter much, but for a car you want to put miles on the 7M valve cover situation leaves a lot to be desired.
 

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I never use the center valley cover any longer.
Took my first one off in '94.
Sealed the big plugs with Toyota gray FIPG, and never looked back.
It promotes good engine house keeping.
And if I run through deep water, it always boils out anyway.
If I am doing a normal engine cleaning, and get water in it, I just use the shop vac to suck it out.
I also can use any plug wires I want, and just order a V8 set with strait (Hemi) ends.
I like seeing things, not covers.
New cars suck with their plastic engine covers.
Made for a woman........
Waiting for them to come with molded in flowers.
 

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^^^^ this. Get rid of that POS cover and those POS valve cover screw "gaskets" and use stainless hardware with lock washers.

BTW my 2UZ Hundy valve covers leaked too. You're the exception if yours didn't.


Sent from my iPhone using Tapatalk
 

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Those POS valve cover screw "gaskets" don't seal anything, as the screws come down outside of the cover gasket.
Never figured out Toyota's thinking on this, other than they had a shit load of them left over from the 4AG, which the studs do enter the oil area.
 

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YotaMD.com author
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Those POS valve cover screw "gaskets" don't seal anything, as the screws come down outside of the cover gasket.
Never figured out Toyota's thinking on this, other than they had a shit load of them left over from the 4AG, which the studs do enter the oil area.
I've always thought it was to distribute the force of the fastener and lessen the likelihood of people cranking down on the bolt/screw and cracking the cast aluminum cover. :shurg: Judging by the grommets and Philips head screws I think Toyota was really afraid of people over-tightening them. Hopefully somebody smacked the engineer that pushed for those features...
 

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I've always thought it was to distribute the force of the fastener and lessen the likelihood of people cranking down on the bolt/screw and cracking the cast aluminum cover. :shurg: Judging by the grommets and Philips head screws I think Toyota was really afraid of people over-tightening them. Hopefully somebody smacked the engineer that pushed for those features...
People should use a torque screwdriver when tightening down the cam covers, so not to exceed the recommended figure in the TSRM.
Just like they should read, and comprehend the complete cam cover installation procedure.
But few ever do.........

I didn't go into detail on why those 'cushion' washers are a bad idea, but part of it is that compressed rubber relaxes over time, and then turns hard.
Either will lead to leaking cam covers.
Both of which are reasons why not to use the cushion washers, or at least check them at least once a month.
 

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Discussion Starter #18
I've always thought it was to distribute the force of the fastener and lessen the likelihood of people cranking down on the bolt/screw and cracking the cast aluminum cover. :shurg: Judging by the grommets and Philips head screws I think Toyota was really afraid of people over-tightening them. Hopefully somebody smacked the engineer that pushed for those features...
People should use a torque screwdriver when tightening down the cam covers, so not to exceed the recommended figure in the TSRM.
Just like they should read, and comprehend the complete cam cover installation procedure.
But few ever do.........

I didn't go into detail on why those 'cushion' washers are a bad idea, but part of it is that compressed rubber relaxes over time, and then turns hard.
Either will lead to leaking cam covers.
Both of which are reasons why not to use the cushion washers, or at least check them at least once a month.
I followed the procedure in the tsrm but torqued them down to 30 with the screwdriver you were talking about. I bought screws and cushions from driftmotion a whole back so should I replace those cushions with lock washers?
 

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Well, 30 in/lbs is almost 50% over what Toyota calls for.
TSRM says 22 in/lbs.

If your rubber bonded washers are not 5-6 years old, just reuse them, they should still be pliable.
But keep in mind, they need to be checked on a regular basis.
Lock washers are my choice. I like the internal toothed ones, as they are meant for low torque aplications, and bite real well.
 
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