M103 Valve job, which guides? Repair size or not?
 

I have a 160k M103 that needs a new headgasket and I'm gonna go and throw new valve stem seals and valve guides. i'm looking in the EPC and I see 2 different repair sizes. how do i determine which one is needed?

I'm just considering to use the standard size and not a repair size since I havent used any repair size seals for the rest of the motor.

no, there is a standard size, repair size 1, and repair size 2 for each intake and exhaust guides.

http://img641.imageshack.us/img641/3231/valveguides.jpg

The guides are offered oversize on the outside in case the bore in the cylinder head is too large for a standard guide. It's impossible to know if you need an oversize guide until the existing guide is removed.

You need to remove the valves and measure the stems with a micrometer. The service manual and technical manual, with all the measurements, have the stem sizes. You can also remove the keepers and springs and do a rudimentary check by moving the valve head back and forth.

The guides can easily be removed and replaced using a liquid CO2 to shrink them. Use new headbolts and lap the valves while your there.

Requires heating the head for guide installation ?
mak

You should be aware that replacing a valve guide will likely require the corresponding valve to be replaced or re-ground and seat to also be re-ground. This due to the new guide moving the center of the seat slightly. Don't waste time lapping valves; if you want a proper job with the best results the valves and seats should be re-ground- but only if needed.

The big thing on removing guides..

Read an aircraft manual. Drill them out till they are thin- they loose press fit and come out easy and less damage to the head.

Manual says to heat head to 80C, liquid N2 the guides. You should have a bore mic or gauge to know how much interference fit there will be.

Measure stems for wear and cut/grind the valve seats and valve faces- lap.

I'd really go for OE guides. TRW or OE valves as needed sometimes the intakes are cheap- $5-10 and then I'd get a full set of intakes.

Michael