# Quick question for Honda Techs



## toms (Nov 17, 2017)

I have a GX390 on my pressure washer that has leaked oil since new. This winter i pulled the engine and took it inside to investigate. It is leaking at the crankcase cover gasket. (one drip every 3 days) So i am going to replace it. My question is "is there anything i need to look out for when removing the cover (like parts falling out etc) or is it a straight forward job. Also does an aftermarket company make thicker gaskets than the pieces of paper that honda uses. This is a genuine Honda GX engine not a Chinese knock off. This engine has never been run but the Honda 3 yr warranty has expired. I dont think i need to replace the Crankcase Seal since it has never been run. thanks for your time


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## JnC (Feb 21, 2014)

The OE honda Gasket indeed is thin where as the ones from ebay tend to be made of a thicker material. I usually apply a layer of permatec gasket sealer on each side before installing it. 



https://www.permatex.com/products/gasketing/gasket-sealants/permatex-high-tack-gasket-sealant/


What I have also noticed is the bottom two bolts on the crankcase cover getting loose due to vibration over time, I usually torque everything even if I am not working on the inside of the engine. 



The cover may give you some trouble coming off as the two locating pins, balancing shaft, crankshaft, cam gear are wedged into their respective bearings in the crankcase cover, a few taps of rubber mallet around the cover along with some gentle persuasion would help. 



The only thing you need to worry about is the cam, if the cam gets pulled from the bearing located on the back side of the engine then the lifters may fall back into the engine, no worries there as they can be popped back into place. Just make sure to align the aligning mark on the cam, balancer and the crank before putting everything back together. 



This video shows what to expect when taking everything apart on a GX390. 



https://youtu.be/cJwrURWouFc?t=720


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## 2.137269 (Nov 15, 2019)

one needs to be careful when thinking of or using a thicker gasket as crankshaft end play is set by the gasket. when i do one i tend to be like JnC states use a thin coat of a good ultra seal silicon sealer on both sides of the gasket 'as to the crank seal, play safe replace it you could possibly?? damage it on disassembly .


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## RC20 (Dec 4, 2019)

Spot on for above.


1 drip every 3 days?. For all the work I would put a rag down.


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## ST1100A (Feb 7, 2015)

Your best sealer is the Hondabond HT gasket sealer/maker. If you can get a tube of that, that is the best by far for using on the case gasket.
I usually take a hammer and a punch and peen around the mating surfaces on both the case and the cover to give the gasket something to grip/bite into, that helps prevent the gasket from sliding out.
Be careful with some silicon type sealers, they can actually make the gasket slippery and it can slide out of place, then you will have a leak.


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## orangputeh (Nov 24, 2016)

you say this has not been run? How about retorquing crankcover bolts and running it? It may expand the gasket and the leak may stop. 

I have used an oil additive for leaks that has worked 3 out of the 4 times I have used it. it's on Amazon best seller commercial grade stop leak for oil. something called ST205 or something like that. I am not a certified mechanic so maybe someone here can tell you if something like this would be safe for your 390.


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