Should I replace head bolts when replacing head gaskets?

[john in ohio]

I'm at 300 hours and took the heads off to clean the carbon from the pistons and check the valves. Should I replace the head bolts or re-use the original bolts?
Where should I use Loctite, I was told that the blue loctite needed a primer when steel bolts go into aluminum?

 

[sgkent]

on a mower engine I would resuse the bolts unless they are damaged or heavily rusted/corroded. Alumium is considered a passive metal. A primer is needed for Loctite to properly cure on an aluminum to aluminum surface, however, you are using steel bolts and that is an active metal. Personally, while I use Loctite and have since the 1970's, I would not use it on a head bolt. When oil, grease, anti-seize is used etc., it causes the torque the bolt actually get to be exceeded by a significant amount. Head bolts already get quite a bit of torque and don't need excess. Sometimes as an engine breaks-in or has high hours, you may want to retorque the head(s), and Loctite may prevent that.

 

[john in ohio]

Thank you

 

[hlw49]

I believe Kohler says not to reuse the head bolts. I have always reused them and never had a problem.

 

[ILENGINE]

I believe Kohler says not to reuse the head bolts. I have always reused them and never had a problem.

Kohler doesn't call them that, but basically they are a torque to yield style bolt. The only ones I alway replaced were on the old K-series, because they had issue of heat related head gasket failure if the bolts were reused.

 

[StarTech]

Why remove the head to de-carbonize when can use use a de-carbonize fluid?

 

[sgkent]

the only decarbonize fluid that ever worked was the GM Upper cylinder stuff that was discontinued. I did a test many years ago of five or six different well known decarbonizing cleaners and the GM one was the only one that actually 100% softened and washed away the carbon. But smoky and stinky. Do it on a windy day so it blows away or you will live in a stinky fog for hours. The carb cleaner one soaks parts in also works but that isn't really designed to be burned. You pour it into the engine slowly at a fast idle, and then stall the engine, let it sit a half hour then restart the engine and pour the rest thru. Probably on a mower 1/8th can per cylinder would be enough. It is outrageously expensive on Ebay. Goes by GM or AC Delco Top Engine Cleaner. The Subaru stuff might be the same. For a $50 - $100 can of the stuff I can buy a head gasket, professionally clean the head(s) in my glass bead cabinet, and then clean the piston dome with some cleaner and scotchbrite. Also check the valves and lap them if needed.

 

[GearHead36]

I used to race go-karts with 5HP Briggs horizontal shaft flatheads. I refreshed the valves every week. I'd remove the head, re-lap and re-lash the valves, decarbon the head & piston, clean up the head gasket surfaces, and put it back together. I never replaced head bolts.

 

[Tiger Small Engine]

I'm at 300 hours and took the heads off to clean the carbon from the pistons and check the valves. Should I replace the head bolts or re-use the original bolts?
Where should I use Loctite, I was told that the blue loctite needed a primer when steel bolts go into aluminum?

Reuse the cylinder head bolts. 300 hours is nothing. If I were replacing the cylinder head gasket I would remove carbon, but 300 hours is low hours.

 

[john in ohio]

After pulling cylinder head number 2 this is what I found!! I was shocked to find this with only 315 hours on the machine! What is this telling me?
I pulled the engine and I have it on a work bench. I didn't open it up yet. Ordering rings and crank seals, should I also order seals for the governor?