Would JB-Weld hold in an engine valve guide.

[Rata222]

I purchased a 1991 Honda Trail 90 non-runner for project to tinker on First off let me say that I am not a mechanic or experienced on engine work. I have been watching a lot of videos and reading to learn . When I disassembled the cylinder and head, I seen that the valve guide was not seated completely into the head. I was able to push it out with a light press of the thumb. It is supposed to be .0015 press fit.
I have been looking at all the correct ways to repair this. I also contacted two cycle machine shops and they said they couldnt do anything - oversize guides are not available. It would be best to find a used head.


Does anyone know if JB-Weld or a high temp loctite product could be used hold the guide in the cylinder head? It is a tight slip fit. Steel guide to aluminum head. I was thinking that the different expansion rate of the two metals would not allow this to work. I know its not the right way - but It would be a cheap easy solution to get the engine running.

Thanks, Jim

 

[benmychree]

How about emphatically, NO!

 

[Aukai]

Is there a way to knurl it?

 

[mmcmdl]

Put some punch marks on the OD and throw some Loctite retaining juice on her and press it in . If you can stake the top where the guide meets the head , you're good to go . I can't tell you how many tractor engines I've fixed this way , and not a one has come back .

 

[darkzero]

I wouldn't use JB Weld or Loctite. If you did & even if it does hold, think about the next time it needs to be replaced.

Is there room to sleeve it?

Are there any clues as to how it got like that? Even though it's got some years on it I can't imagine that to wear out like that. Can you tell if someone caused damaged or used the wrong part?

I would take it to a machine shop (engine machine shop) or someone who specializes in dirt bikes or whatever it is & have them take a look. Or if it's just something you don't care much about & just want it running, have at it.

 

[acruxksa]

Honda 90 parts are pretty common and cheap chinese honda 90 parts are even more common although they're hit or miss on fitment to an original Honda engine. Also, cheap chinese knockoff honda 90 engines are also available. Not sure on your budget or intentions. I totally get where you're coming from, but if it was mine, I'd bite the bullet and get a replacement oem honda cylinder head. Yes it's far more expensive than JB Weld, but in the end, honda engines run trouble free for a very long time and keeping that dependability would be one of the most important benefits to owning the trail 90 in my opinion. (I've owned a trail 90, a trail 70 and a honda rancher 350 atv, as well as several honda outboards and generator, so I may be a little biased.)

 

[Cadillac]

I’ve ran across this problem over my years as a mechanic. Seen it in 18hpBriggs engines and club car engines. I’ve dealt with it acouple ways and never used loctites or know weld for repairs.
One way would be to stake the id of the aluminum head, once guide is inserted I would punch around the guide to swell the material so it couldn’t come out again. I’ve knurled the outside of the guide then pressed back into head then reamed bore of guide to size.
The problem happens when the engine is allowed to overheat. Aluminum expands in the head and the thrashing of the valveknocks it loose and Pulls it out. Also done to valve seats with good results.

 

[HarryJM]

Please excuse my little dissertation of value guide repair.

What every fix you do will probably (in my opinion) require regrinding/cutting the valve seat to make sure you have the proper contact between the valve and valve seat. There are three different angles to a Honda (as others) value seat and you want to get the middle of the valve seated (actual seating surface) with the middle valve seat angle. You will also have to lap the valve to the new valve seat or in this case your current one after fix. I replaced many a value guide during my 10+ years as a motorcycle mechanic (mostly Honda) and had my own set of Newway valve seat cutters to recut the 3 different value seat angles so that contact between the value face is in the middle of the valve seat (basically raising/lowering the value seat center angle).

The above described method is part of what you pay for when having and value guide replaced. As with anything are many solutions for a give problem and in no way do I want to diminish what other forum member have suggested.

During my short tenure as a motorcycle mechanic I worked on a straight commission basis and learned early on that it was not worth it to take short cuts as I had a good reputation in all of the shops I worked and a returned job just cost me money that I was not earning on anther job. Now on a different note the repairs I did to my own motorcycles (Honda, Norton, Harley) included what I would call some good old backyard mechaning.

In theory if the value guide is not seated securely/correctly inside the head you have the possibility of it coming loose while the engine is running which could allow the valve guide to drop down and maybe cause the engine to lock up which is not something you want to happen while driving down the highway, or burn up the value. Given that you may only be putzing around in the woods that may not be all that dangerous.

This is a good explanation https://www.austincc.edu/wkibbe/headdesign.htm#:~:text=Honda uses the 30-45,GSR, ITR, and CTR.

 

[doc55]

How about emphatically, NO!

I disagree it most certainly would hold it use 620 the shear strength is around 4,000psi and a working temp up to 500 degrees. The stuff will mount it better than a press fit.

 

[FOMOGO]

500 degrees is just not going to cut it for a valve guide. in an air cooled engine you will likely see temps double that at the the valve. Mike

I disagree it most certainly would hold it use 620 the shear strength is around 4,000psi and a working temp up to 500 degrees. The stuff will mount it better than a press fit.