List of things to change during head gasket

[gawsies]

Looks like i'm going to be changing the head gasket early next month, what should i change while im there? bolts? seals?

thank you

[wwdwgs]

Download PET parts catalog for reference, if you haven't done this before and wait for a loooong list.

[walfreyydo]

If you are pulling the head, its a really good time to do the following (most of this done by a qualified machine shop):

-valve job (cut seats grind valves)
-check and if needed replace guides
-valve stem seals
-check and if needed replace lifters
-check head for flatness and if needed resurface
-check buckets/shims/valve stem height (needed after a valve job)

Look for a "head gasket seal set" - it will have all/most of the seals you will need so you dont have to go hunting for each and every seal individually

[Jfrahm]

Consider alternator bearings: replace or add a little grease. Check the brushes, maybe get a new quality voltage regulator.

AFM re-track.

Refurbish the fuel injectors, can be done at home with a rig to backflush them.

Fuel lines, if needed.

If the heater valve is at the back, good time IMO to replace it. There are some nice stronger alternatives to OEM style.

Re: valve guides, I am curious about the re-lining process they are doing now. Bore out the OEM, swage in a ductile iron liner, ream to size. I am also curious about knurling and how long that might last. Seems like not long, but some say it'd hold more oil and last a long long time? It's a divided issue, but a big factor is if the knurls are rolled vs. cut.

-Joel.

[OK-944]

In addition to the above - look for excess scoring of cylinder walls, excess carbon buildup on piston heads, find the spring-loaded anti (oil) drainback valve near the back of the head, and press on this with a pin or narrow drift to make sure its moves and is not clogged. Evaluate the condition of the O-ring behind the camshaft gear and consider replacing it, which will require the (sometimes difficult) removal of the cheesehead bolt at the front of this assembly.

Also...check the hoses underneath the intake manifold and replace if necessary (would recommend just replacing these regardless).

[walfreyydo]

Originally Posted by Jfrahm

Re: valve guides, I am curious about the re-lining process they are doing now. Bore out the OEM, swage in a ductile iron liner, ream to size. I am also curious about knurling and how long that might last. Seems like not long, but some say it'd hold more oil and last a long long time? It's a divided issue, but a big factor is if the knurls are rolled vs. cut.

-Joel.

I dunno man, I just had them install the oem porsche ones on my 968 head project I am currently working on. Only needed new exhaust guides, intakes were ok. Guides werent overly expensive (~$100).

[Monkey Wrench]

I took my 66 volvo head with newly installed valve guides into a decent engine shop that works with race engines and had him install stainless steel seats and look after doing a proper 3 angle valve grind, I had polished the ports myself as well..

he could have reamed them , there was enough meat and he had good tooling, but he suggested I have him knurl them as well because it will hold the oil better. I went ahead with his suggestion and had no regrets.

if you do a great job on the head and improved compression it may burn oil if the rings and the bore aren't right so its a bit like doing half a job. the full job costs more so I do not think this is necessarily a bad plan, if you do the rings youll probably do the bearing shells, then will you turn the crank? new cam? will you have it balanced? new pistons, oil pump? it amounts to how deep your pockets are.
I think the most fun way is to just "do it right" and spare no expense but that might not be agreeable to the CEO of your household ;-)

[Monkey Wrench]

I took apart a early 70's volvo , it was a real beater I paid about 100 for.. and didn't want to spend any cash on it. it had a big hunk missing from an exhaust valve..

I found another valve and it had a larger stem.. so not having a reamer I just picked the closest drill bit and drilled out the guide to roughly fit, machined the valve head to fit, lapped the valve in, put it back together..

it ran ok but it used a quart to get to work and another quart to get home lol, if anyone tailgated I could step on the gas and create an oil fog.. the fun lasted as long as my supply of used oil but I did use some of its parts again.

I had an engine shop say .004 of slop was ok..

if you do valve grinding and such I;d pay attention to the valve spring length because as the valve changes depth so does the sprung and unsprung length. I found I had valve float issues and putting shims under springs fixed that. its worth taking some measurements. I found that it dint take much thickness under the spring to make a big difference to the valve float but if you put too much you could get the spring coil bound. I found I needed about the clearance of a postit note between each coil when compressed, to make sure that didn't happen.

sure that's a redneck way ;-) but you could make careful measurements and do things more by the book if so inclined, I'm sure.


one might make a careful measurement of the distance from the head to the top of the valve stem or to the keeper and use that as a reference, maybe.

if you send the engine for a valve grind the distance may be altered. Its probably not hurtful just to know where you started to be able to make sense of any change in valve stem position after any headwork. any machining of the valve will lift it up slightly further into the head and make the spring more loose. Its possible to have new seats installed, I had stainless seats installed in my 66 Volvo.. the lead was removed form fuel and that helped the valve seats,, The theory was stainless seats would fare better with the newer unleaded fuel.

I'm still not sure if burning lower grade stuff with a bunch of alcohol or techron is good, or if it means less lubrication. It seems to be promoted as cleaning your fuel injectors but the fuel injectors aren't really the most expensive part of an engine.. What does it do to the bore and the pistons over the long term?