Replace Head bolts

[JC53]

I have a Ford Lehman 120. Blown head gasket. After disection found one of the head bolts had been broken. Probably during a PO rebuild some time ago. I’m now looking at replacing all the bolts. My question is what kind of bolts do I need? They don’t look all that special, but I’m no country bumpkin. Anybody in this illustrious group got experience with this? Thanks in advance.

 

[psneeld]

When I asked American Diesel...I think they said they were difficult to find bolts and their cost was something like 28 dollars a bolt.

BOMAC might have them cheaper...


But everyone has said, just reuse the ones you have.

 

[Comodave]

When I took the seminar from Bob Smith he talked about the 120 head bolts. Since I didn’t have 120s I really didn’t pay close attention. He did say that one of the engines should not have head bolts reused or retorqued. I would check with Brian and see what he says. I just don’t remember what Bob said as to which he was referring to, the 120 or maybe the 135.

 

[psneeld]

Brian said reuse a couple years ago. Several top notch mechs/engineers did too. Pretty sure Ski agreed but hopefully he will chime in.

 

[Comodave]

Like I said I wasn’t really paying attention since it wasn’t my engines so I may be wrong, just not sure.

 

[kchace]

When I took the seminar from Bob Smith he talked about the 120 head bolts. Since I didn’t have 120s I really didn’t pay close attention. He did say that one of the engines should not have head bolts reused or retorqued. I would check with Brian and see what he says. I just don’t remember what Bob said as to which he was referring to, the 120 or maybe the 135.

The 135 should not have its head bolts retorqued. There is a strongly worded warning against doing it in the 135 manual.

Ken

 

[Comodave]

Thanks, I was pretty sure he said something like that but I couldn’t remember what engine it was, just that it wasn’t on the SP225s that I have.

 

[SoWhat]

Don't retorque head bolts, but certainly check the torque every 1000 mi. Bolts can work loose. Check before setting valve lash.
You can reuse head bolts as long as they are not rusty or have damaged threads.
Rusty bolts will probably need more torque to clamp the head to the block.
New head bolts are not special and should not be that expensive.

 

[BruceK]

We retorqued head bolts on my 120s, no problems.

 

[psneeld]

I believe the difference between 120s and the 135s and other make engines....

From what I was told is there are standard bolts and stretch bolts. Regular bolts are reusable and can be retorqued, stretch bolts are one time use, one time torque.

Not being a mechanic I don't know, but that's what I learned along the way.

 

[psneeld]

This was just passed along to me....

 

[OldDan1943]

If you want to re-torque the head bolts, first loosen them and then torque them.

 

[av8r]

If you want to re-torque the head bolts, first loosen them and then torque them.

I’d like a citation for that information, I don’t think it is correct. It is contrary to the engine manuals I am familiar with, including the Lehman maintenance manual and overhaul manual.

 

[catalinajack]

Just two weeks ago I was at American Diesel in person and talked to Brian Smith specifically about re-torquing the heads on a FL120. First of all, it should be done every 500-1,000 hours with the valves adjusted after the heads have been re-torqued. The procedure is to loosen them one at a time and then torque to the spec (110 ft/lbs) in the order shown in the manual. The FL135 should not be re-torqued. The valves on the FL120 should not be adjusted without doing the heads first.

 

[OldDan1943]

I’d like a citation for that information, I don’t think it is correct. It is contrary to the engine manuals I am familiar with, including the Lehman maintenance manual and overhaul manual.

Citation: US Navy. Reasoning, any paint or rust on the threads may give you a false torque reading.

Again, US Navy: There are some bolts that are torqued via the 'flats method' also. This will ensure equal pressure on a metal to metal fit (no gasket). Draw them up equally tight and then, tighten each bolt one flat at a time (on the nut). The manual will tell you/us how many flats to torque it.

We will no doubt never experience this method of torquing on our recreational engines. I just wanted to expose you to another method of torquing a bolt or nut.

 

[SoWhat]

This was just passed along to me....

You will not find TTY bolts on Lehman's. I believe they entered the market in 2009?

 

[sdowney717]

You will not find TTY bolts on Lehman's. I believe they entered the market in 2009?

That is good because TTY bolts stretch and can not be reused.
Does ARP make head studs for this application, likely pricey, but they are popular with diesel truck engine people.

 

[Choices]

Why not take one to a Ford tractor distributor?

 

[OldDan1943]

Why not take one to a Ford tractor distributor?

Dont tell them the bolts are to be used on a boat.