2013 4JJ1 engine with rocker cover oil leak

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rwally
Posts: 35
Joined: Mon Jan 19, 2015 12:44 pm
Location: Perth, WA

2013 4JJ1 engine with rocker cover oil leak

Post by rwally »

I have an oil leak on the rear of the rocker cover gasket. The head gasket was replaced 20,000 kms ago by a dealer. I asked them to retain all replaced parts and one set of those is the rocker cover gasket and two half moon rubber plugs so I presume that's what they renewed. Today I removed the rocker cover to try and locate the cause of the leak.
All looked okay except for two things:
(1) the gasket has two indentations matching two blobs of orange sealant on the face of the head, one each side of one of the rear half moons. I'm guessing the gasket did not seal properly over these blobs and so that is the cause of the leak. Would you guys/gals agree?
(2) I see there are actually four half moon plugs not two so I wonder if the dealer never replaced the rear two. Is it perhaps usual practice to only replace the front two?

I removed the orange blobs, scraped clean the half moon joins on all four half moons, smeared some gasket sealant over all four half moons and over the entire face of the rubber gasket on the cover. I did not replace the cover gasket. All is now re assembled so only time will tell whether I've fixed it.
I started the engine and left on idle to check for leaks. Out of curiosity I removed the oil filler cap (for less than 5 seconds!) and was surprised to find oil splattering out of the hole. It even splattered oil over the outside surface of the passenger side front fender. Is this normal or does it indicate an excessive crankcase pressure and hence pressure forcing oil out of a weak spot on the rocker cover gasket?
mydmax
Posts: 1807
Joined: Sat Oct 12, 2013 8:36 pm

Re: 2013 4JJ1 engine with rocker cover oil leak

Post by mydmax »

rwally
If the blobs of sealant have indented the gasket, then it was OLD gasket sealant and the cam covergasket simply bolted down onto it. Slack springs to mind. If there is NO evidence of sealant under the half moon plugs then they definitely didn't remove/replace/reseal them.
Usual practice is to do a job as quick as possible and use as little of resources (gasket sealant) as possible to get the vehicle out the door. Unless the whole job is performed meticulously such leaks WILL happen afterwards. In horse terms, ODDS ON.
I think your assessment of only two 1/2 moons replaced is accurate.
If they didn't see the rear ones, they will look old to you and have no new sealant under them, then the repairer needs attending SpecSavers asap. Obviously a skilled mechanic, or one who takes short cuts.

Which sealant did you use?
If you remove the filler cap when running, you will get oil splattered out of the hole as the cams and rotation plenty of oil being delivered to cam lobes etc, and the pumping of pistons which are causing fast and positive pressure changes will cause oil to exit. If there was excessive crankcase pressure , your oil leak mentioned earlier would be significant loss/ I don't think that is a problem. An leak or being forced, out is two different conditions.
rwally
Posts: 35
Joined: Mon Jan 19, 2015 12:44 pm
Location: Perth, WA

Re: 2013 4JJ1 engine with rocker cover oil leak

Post by rwally »

mydmax wrote: Sat Jun 05, 2021 1:18 pm Slack springs to mind.
You are much more diplomatic than me mydmax. I say that they are incompetent lying crooks - this is a major Isuzu ute dealer here in Perth that has been mentioned in previous posts.
I used a Loctite flexible gasket sealant in a tube. It's black but I suppose 90% of them are.
I could not see whether the rear half moon plugs had new or old sealant under them - even with my inspection camera.
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