Re-building an Onan B43G from a JD 318 mower for a friend of mine (regretting committing to it). While cleaning it up I had an exhaust valve seat fall out. The seat is at an angle so peaning the sides to hold the seat would be very tough. Would Loctite retaining compound hold it there? Thanks
- Thread starter Bkpigs
- Start date
Steve@Advance
Well-known Member
No, nothing I know of will handle the heat.
It will need to go to an automotive machine shop and have an oversize seat put in.
It will need to go to an automotive machine shop and have an oversize seat put in.
I've seen several Onan's do that, but usually a P model. The only real solution is either an oversize seat installed by a competent machine shop or a replacement block. depending on your local shop charges, a used block may be cheaper.
I know of no adhesive or filler that will hold it.
I know of no adhesive or filler that will hold it.
I went to all the remaining automotive machine shops in Rowan County NC looking for someone who could put an intake valve seat in a p218g a
few years ago and nobody thought they could. I am thinking that it was 18" from one head to the other on the block and it wouldn't fit into
anyone's head machine.
A Job-shop machine shop may be willing to tackle it, they would probably have to look at it first, but you will have to pay their price.
At that time, Onanparts.com had an oversize valve seat, but it had to be bored to fit whichever valve you were replacing the seat for.
few years ago and nobody thought they could. I am thinking that it was 18" from one head to the other on the block and it wouldn't fit into
anyone's head machine.
A Job-shop machine shop may be willing to tackle it, they would probably have to look at it first, but you will have to pay their price.
At that time, Onanparts.com had an oversize valve seat, but it had to be bored to fit whichever valve you were replacing the seat for.
Before seat & guide machines, we used a Kwikway portable seat machine that was very accurate. To mount the machine on a small engine all you need is a thick flat plate and adapt it to the head bolts. Use your head gasket to mark your plate and a cutout in the plate of the valve seat area. Recess your holdown bolts,we used allen head bolts. Using Martin Wells "W" series seat and correct press fit you can save your engine.Email if you have questions.
Butch(OH)
Well-known Member
Sorry no $10 fixes for that. That area gets too hot for any glue to hold the seat in place. Peening doesn't work either other than short term. Heat must transfer to the head to prevent overheating of the seat and peening it causes it to lose contact area, thus it overheats, and expands more than the block, and thus quickly loosens again. The only fix is an oversized seat and the dollars it takes to get it done, sorry. My tooling is K-line and pilots on the guides. Seats are cheap but an oversized seat requires the correct sized cutter and $$. Even at my cheap rates most of those go back home with the owner without being left at the shop. All can be done on a knee mill with a boring head but the set up would be super tedious, a job for a retired machinist with nothing but time on his hands and a Bridgeport in his shop.
The great bulk of the time these days opening up an Onan for any reason leaves a guy with the same feelings you have,, sorry. Parts are ridiculous expensive and add a bit of machine work and you have one large money pit.
The great bulk of the time these days opening up an Onan for any reason leaves a guy with the same feelings you have,, sorry. Parts are ridiculous expensive and add a bit of machine work and you have one large money pit.
Lumbersawyer
Member
- Location
- Grand Rapids, MN
I installed new seats in the exhaust valves of my GP John Deere block with a Bridgeport (they are a flat head engine). The valves are at 4 degrees angle. Any competent machinist should be able to cut an oversize seat into your block.
rustyfarmall
Well-known Member
I tried the Loctite trick on an 8 horse Briggs. Loctite recommended by a machine shop owner. It lasted for one session of mowing.
On a side note to this loose valve seat issue. Do they still have the rubber grommet installed in the shroud around the oil filter ? Is was told that if that is gone that side will not cool good enough from air escaping and can promote loose valve seats on that side of the engine.
dr sportster
Well-known Member
That is about .004" interference fit .if it falls out you don't have proper fit and it needs a larger seat.
Glen in Iowa
Member
If I recall correctly, the block needs to warmed up 350 degrees for any seat to have a good tight fit that will last.
wrenchere85
Member
I had a Briggs V twin on a mower, have a valve seat come loose. I put it back in and peened all around it. It lasted about
1 week. Then I took the head to local auto machine shop, guy took valve seat and knurled the outside with a hand held
knurling tool, then reinstalled. Then he checked to make sure valve seat was aligned with the guide and valve was
sealing.This all took about 15 minutes while I watched. Cost was $1 a minute, $15. Still has not come loose, 5 years
later.
1 week. Then I took the head to local auto machine shop, guy took valve seat and knurled the outside with a hand held
knurling tool, then reinstalled. Then he checked to make sure valve seat was aligned with the guide and valve was
sealing.This all took about 15 minutes while I watched. Cost was $1 a minute, $15. Still has not come loose, 5 years
later.
Similar threads
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.
Copyright © 1997-2024 Yesterday's Tractor Co.
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy