Changing Valve Seats, does that require new rings for the Pistons?

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hisandhers80s

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Have a 4/1994 FZJ80 with 240,000 miles and about to pull the head off to do head gasket. Someone I was talking to about it, said I should probably replace the piston rings due to their age when replacing the valve seats. Just trying to see what the prevailing wisdom is here. Also, I think this is the first time the head gasket has been replaced, but will be able to confirm for sure later this week when the head comes off.
 
doing the head gasket & associated valve work can be done with the block in the car (simply remove the head)
to do the rings youd need to remove the entire engine from the car, a big difference

provided you have run clean oil & air filters and not exhibiting normal worn ring symptoms you shouldnt need to do the rings. When the head is removed the condition of the bores should also give a good indication to the state of the rings IMO.
I did the HG on mine 8 years ago at 300,000miles and the rings are still original and all is fine.

are you using much oil or is this preventative maintenance?
 
robnicko said:
doing the head gasket & associated valve work can be done with the block in the car (simply remove the head)
to do the rings youd need to remove the entire engine from the car, a big difference

provided you have run clean oil & air filters and not exhibiting normal worn ring symptoms you shouldnt need to do the rings. When the head is removed the condition of the bores should also give a good indication to the state of the rings IMO.
I did the HG on mine 8 years ago at 300,000miles and the rings are still original and all is fine.

are you using much oil or is this preventative maintenance?
Click to expand...
I was losing oil from around the timing cover, oil pump cover, rear main seal, and the upper oil pan gasket. So since I removed the transmission, I figured it was smart since I was this close, and go ahead and do the head gasket, so I don't have to worry about it for a while. I was planning on leaving the block in the engine bay and just removing the head and taking it to the machine shop, and have them machine it and replace the valve seats since it comes in the gasket kit. The plan was to look at the bores once I got the head off for wear, etc. but was just curious if doing rings at the same time was normal or only if it needs it.
 
I replaced a blown headgasket two years ago, on one of my '95s, and had the valve seats replaced at the machine shop at the same time. Before the work it was using/losing about a quart every 3,000 miles, which is about what my other two 80s use. All three have around 300k on them. After the head refresh, the 80 uses no oil at all. I didn't touch the lower end.

IME, the lower ends of the 1FZ-FE engines are pretty good for 500k, if they are taken care of in the interval.

I would never replace a head gasket for the hell of it. It has to be replaced if it's blown, of course, and whenever the head is removed for valve work.
 
I had the upper and lower intake off, alternator, starter, radiator, and valve cover off, along with the transmission and transfer case for the rear main seal and transfer case rebuild. It seemed logical since I was this close and has 240,000 on the clock to do the head gasket.
 
@hisandhers80s : Are you referring to replacing the valve seats or valve stem seals??

Not the expert but IME for a routine head gasket replacement the valve seals are always replaced, the valve seats are checked and machined to spec (by a machine shop) and often don't need to be replaced unless they're worn (recessed too deeply), damaged, burned/melted or you just want to start with new.

The valve stem guides are usually not replaced unless they're out of spec (worn).

The valves themselves can often be reused ie: cleaned then checked for wear in a few places then the outer edge (the part that seals against the valve seat) is ground to spec

The piston rings are not replaced when just replacing the head gasket (and valve stem seals) unless you find damage/wear of the cylinder wall, rings, etc, etc and then you're doing a full engine rebuild ( @Fj80oregon )


Here's a video showing the valve stem seals being replaced:




Another which is part of a Series done by OTRAMM:






Here's Part 1 of a full head gasket video Series by OTRAMM:


80 Series Land Cruiser 1FZ-FE Head Gasket Part One - https://www.youtube.com/watch?v=9CVK5lr2iHc
 
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Kernal said:
@hisandhers80s : Are you referring to replacing the valve seats or valve stem seals??

Not the expert but IME for a routine head gasket replacement the valve seals are always replaced, the valve seats are checked and machined to spec (by a machine shop) and often don't need to be replaced unless they're worn (recessed too deeply), damaged, burned/melted or you just want to start with new.

The valve stem guides are usually not replaced unless they're out of spec (worn).

The valves themselves can often be reused ie: cleaned then checked for wear in a few places then the outer edge (the part that seals against the valve seat) is ground to spec

The piston rings are not replaced when just replacing the head gasket (and valve stem seals) unless you find damage/wear of the cylinder wall, rings, etc, etc and then you're doing a full engine rebuild ( @Fj80oregon )


Here's a video showing the valve stem seals being replaced:




Another which is part of a Series done by OTRAMM:






Here's Part 1 of a full head gasket video Series by OTRAMM:


80 Series Land Cruiser 1FZ-FE Head Gasket Part One - https://www.youtube.com/watch?v=9CVK5lr2iHc
Click to expand...

Yes, sorry I was using the wrong term. I should have said seals and not seats!
 
if your head and transmission are both off this is the perfect time to replace your rear heater lines if they are rusty and desired.
 
60 toy ota said:
if your head and transmission are both off this is the perfect time to replace your rear heater lines if they are rusty and desired.
Click to expand...
Rear hear core has been removed. Will be removing the rear heater lines to get them out of the way.
 
Did not see it mentioned yet but with head gasket and valve seals, you would want to look at trimming chain guide and slippers. Your vintage has had documented issues of breaking, while you are in there
 
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