Failing Valve Cover Gasket? (1 Viewer)

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I’m getting oil spatters on the manifold heat shield. Is this a sign of a failing gasket?
The heat shield was spotless a couple months back and now it’s got (at least what I think is) oil spatter on it.
I thought maybe a breather hose from the head, but everything looks in place.
Anyone have this happen? Don’t see much in the Mud archives.
Dan

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I’m getting oil spatters on the manifold heat shield. Is this a sign of a failing gasket?
The cover was spotless a couple months back and now it’s got (at least what I think is) oil spatter on it.
I thought maybe a breather hose from the head, but everything looks in place.
Anyone have this happen? Don’t see much in the Mud archives.
Dan

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Curious. Hard to tell by the pics, but don't see any seepage down the side of the head - which should be happening if the cover gasket is the source of the splatter.

IIRC, there is no torque spec for the valve cover bolts. Or if there is, after [some amount of] running they will become (nearly) hand tight as the gasket slowly compresses over time and heat cycles. (how I found mine @ purchase)
Give 'em a tightness check and maybe cinch them down a bit more - not too tight tho.
Wash down the area of splatter, go driving a bit and re-eval for the source.
 
Could be. Probably good practice to replace the valve cover gasket and PCV valve and grommet anyway if they haven’t been done a while.
Are there other ways to check
Curious. Hard to tell by the pics, but don't see any seepage down the side of the head - which should be happening if the cover gasket is the source of the splatter.

IIRC, there is no torque spec for the valve cover bolts. Or if there is, after [some amount of] running they will become (nearly) hand tight as the gasket slowly compresses over time and heat cycles. (how I found mine @ purchase)
Give 'em a tightness check and maybe cinch them down a bit more - not too tight tho.
Wash down the area of splatter, go driving a bit and re-eval for the source.
There’s only 60k on this gasket. But like you said there’s nothing leaking down the side of the head. It’s splattered like a small amount of oil is getting blown back from the fan. The stains run the entire length of the head.
The PCV hoses just have a little bit of moisture around the connecting points. This is bugging me. I had this engine bay spotless a few months back.

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Are there other ways to check

There’s only 60k on this gasket. But like you said there’s nothing leaking down the side of the head. It’s splattered like a small amount of oil is getting blown back from the fan. The stains run the entire length of the head.
The PCV hoses just have a little bit of moisture around the connecting points. This is bugging me. I had this engine bay spotless a few months back.

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I’d probably start by cleaning the engine with simple green (careful of dizzy, alternator, etc.), then drive it for a bit and see if you notice any oil seeping out of the valve cover.

It could also be the front main, oil pump seal, or dizzy o ring, especially if it’s getting blown back by the radiator.

How much oil are you having to add?
 
I’d probably start by cleaning the engine with simple green (careful of dizzy, alternator, etc.), then drive it for a bit and see if you notice any oil seeping out of the valve cover.

It could also be the front main, oil pump seal, or dizzy o ring, especially if it’s getting blown back by the radiator.

How much oil are you having to add?
Almost never need to add between changes. 60k on rebuilt both ends.
Could oil be getting in the exhaust and there’s an exhaust leak as well that is blowing it out? It doesn’t sound like an exhaust leak though.

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Almost never need to add between changes. 60k on rebuilt both ends.
Could oil be getting in the exhaust and there’s an exhaust leak as well that is blowing it out? It doesn’t sound like an exhaust leak though.

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I’m not sure about that, most muffler shops will do a free diagnosis if you suspect an exhaust leak though.
 
IMHO I would not use Simple Green or Purple Power on anything that's still attached to the vehicle, and then I would only use something like that on metal bits. Those are strong cleaners that can/will damaged paint and rubber/plastic parts if not used correctly. Safer IME to just use car wash soap.

Have you removed the spark plug wire covers to look underneath for oil? Pull a couple of spark plug wires off the spark plugs and look into the spark plug tubes for oil? If you find oil in those locations it's likely from the spark plug tube seals.

Either way, that's a very clean engine, before you cleaned it.
 
IMHO I would not use Simple Green or Purple Power on anything that's still attached to the vehicle, and then I would only use something like that on metal bits. Those are strong cleaners that can/will damaged paint and rubber/plastic parts if not used correctly. Safer IME to just use car wash soap.

Have you removed the spark plug wire covers to look underneath for oil? Pull a couple of spark plug wires off the spark plugs and look into the spark plug tubes for oil? If you find oil in those locations it's likely from the spark plug tube seals.

Either way, that's a very clean engine, before you cleaned it.
I tend to used dish soap on the engine because it’s kinder to the rubber hoses works pretty well. I did pull the wires and I noticed some oil in there. You think the oil is making its way out of the plug tubes and onto the exhaust side of the engine?
 
Oil can be like blood from a head cut. A little goes a LONG way :oops:
With all the engine bay airflow the oil could be originating from anywhere and blown back by the fan. Is the fan oil stained?
Get underneath and check for telltale drips. Sump, oil pump cover, front main seal, oil level sensor, PS pump/hoses, aircon pump, distributor, fan hub etc etc
How is the underbonnet heat proofing (wet/saturated)?
Could be from an external source flicked up off the road.
Hubs, brakes?
Check gearbox/tranny and rear of the engine. Could be getting blown up/forward from down there.
 
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Oil can be like blood from a head cut. A little goes a LONG way :oops:
With all the engine bay airflow the oil could be originating from anywhere and blown back by the fan. Is the fan oil stained?
Get underneath and check for telltale drips. Sump, oil pump cover, front main seal, oil level sensor, PS pump/hoses, aircon pump, distributor, fan hub etc etc
How is the underbonnet heat proofing (wet/saturated)?
Could be from an external source flicked up off the road.
Hubs, brakes?
Check gearbox/tranny and rear of the engine. Could be getting blown up/forward from down there.
The truck is bone dry everywhere. Just maybe a little moisture on the PS from the reservoir house but not a drip anywhere, which is exactly why this is bugging me so much. If there were some drips somewhere I would assume they’re blasting through the engine bay.

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Power steering ?pump appears to have a small leak, but unlikely for that to find
it's way over to the upper right side of the engine.

If the valve cover gasket and spark plug tube seals haven't been replaced in ?10+ years (or unknown) that's one place to start.

There is a rare cause of an oil leak not related to the valve cover gasket or tube seals, a crack in the valve cover itself.

Either way, your leaks appear to be very minor.
 
Power steering ?pump appears to have a small leak, but unlikely for that to find
it's way over to the upper right side of the engine.

If the valve cover gasket and spark plug tube seals haven't been replaced in ?10+ years (or unknown) that's one place to start.

There is a rare cause of an oil leak not related to the valve cover gasket or tube seals, a crack in the valve cover itself.

Either way, your leaks appear to be very minor.
I think you’re right, I have a feeling it’s the tube seals. Has to be. I would think that when Toyota rebuilt the head they would replace the tube seals, but… The PS has been a PIA. The hose from the reservoir leaks where it connects to the pump no matter what I do to tighten it.- I’m sick of messing with it.
 
There is a small O-ring behind that side pipe that hardens and leaks, tightening the 10mm bolt won't help, you need to replace the O-ring.

Just remove the 10mm bolt, wiggle the pipe out of the pump ( be ready to catch some of the PS fluid), you do not have to remove the hose.

Then remove the old O-ring off the pipe with a small pick, clean off that area (don't leave pieces of the old O-ring stuck inside), slide a new O-ring over the end of the pipe, then slide the pipe back into the pump, tighten the 10mm bolt, done.

If you want to be OCD about it you could also buy a new 10mm bolt with the O-ring from your local Toyota dealer parts professional. The bolt has an attached lock washer which IME can sometimes lose it's tension (any bolt with a lock washer).
 
Any chance you dropped a drip of oil when checking PS/Engine/Tranny dipsticks?
 
If you're doing the spark plug tube seals (which requires removing the valve cover) you'll also want to replace the valve cover gasket, the PCV valve grommet, and the Throttle Body gasket.

And to remove the Throttle Body you have to disconnect a small diameter water bypass hose from the underside of the TB, so it's easier to go ahead and replace that hose if it's age is unknown while you're in there.

And while the TB is off it's easier to clean out the 25 years of sludge/carbon
that builds up in the TB and on the butterfly valve. You can also reach in and to some degree clean up some of the intake plenum.

And if your EGR system is still intact you could clean out the EGR port/passageway where the gases flow from the EGR valve to just behind
the Throttle Body.

And while you're doing that you can remove the EGR valve and clean the carbon out of that, check it's function, replace if necessary.

And with all that out of the way you can inspect and rewrap your engine harness where it comes close to the hot EGR pipe and then add a heat reflective/insulation sleeve.

And to get the valve cover off you might as well remove and replace the heat control valve on the firewall while you're in there (if it hasn't been replaced) and then the hoses connected to that, if not the rest of the heater hoses in that area.

And don't forget to clean out the oil baffle located on the inside top of the valve cover; that can become clogged with sludge which is difficult to clean out, one can of Brake/Carb cleaner won't be enough. That's where some Simple Green or Purple Power can help.

And heck, if it hasn't been done yet, might as well replace the distributor O-ring.

So one job can turn into 12, 14, 20---, while you're in there.:)
 
And heck, if it hasn't been done yet, might as well replace the distributor O-ring.

These DO tend to leak. Mine for some reason would start leaking every 4-5 years. Pull the dizzy, O-ring would be rock hard and not fully sealing any longer. Not a major leak....but annoying.

So while I had my distributor out doing my head gasket I cut a second O-ring groove and double O-ringed it. Time will tell if it made any difference....but a nary a drop of oil so far (2 years into it).

I know......I know......

The things a man will do when retired and you have the time...........🙄

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There is a small O-ring behind that side pipe that hardens and leaks, tightening the 10mm bolt won't help, you need to replace the O-ring.

Just remove the 10mm bolt, wiggle the pipe out of the pump ( be ready to catch some of the PS fluid), you do not have to remove the hose.

Then remove the old O-ring off the pipe with a small pick, clean off that area (don't leave pieces of the old O-ring stuck inside), slide a new O-ring over the end of the pipe, then slide the pipe back into the pump, tighten the 10mm bolt, done.

If you want to be OCD about it you could also buy a new 10mm bolt with the O-ring from your local Toyota dealer parts professional. The bolt has an attached lock washer which IME can sometimes lose it's tension (any bolt with a lock washer).
Is this the bolt with the o ring that you are referring to which should be replaced ?

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