Max Head Distortion

Post by **JPM** » 26 Aug 2017, 09:47

Hello All,

2004 V70, 240,000 miles, B5244S, coolant in cylinders, head gasket transplant underway.

I'm seeing about .005" max distortion on my cylinder head, between cylinders. I've read that the tolerance in VIDA is .5mm (about .020"), but that sounds wrong to people, including myself.

Should I slap it together with my new gasket from IPD, get the head skimmed, or just throw the whole thing away?

Your insight and opinions are most welcome!

Thanks in advance,
Jonathan

EDITED: 0.5mm is what I meant.

Post by **SuperHerman** » 26 Aug 2017, 14:18

I would ask your machine shop if skimming the head can get it flat and check for cracks or other damage that once serviced cost too much. It seems like the head is fine from your measurements, only a skim will improve things. I would get a complete head gasket set and lap the valves and change the valve stem seals.

Why did the head gasket fail? Overheat or just age? I did a HG from an over heat - had it machined and did the lap and valve stem seals with great results. Total cost was $250 in machine work and cleaning (this shop was expensive but I paid more for ultrasonic cleaning as the head and valve cover were very dirty. Usually a clean and skim costs $100.00. Getting a new head opens up many issues with the cams, VVT and the like.

That said if everything cleans up nicely I would stick with what you have and refresh the head. Now if you have terrible wear on the cam or journals that is another factor.

Post by **kallekula** » 26 Aug 2017, 14:26

My machine shop said 8-10 thousands of an inch was borderline machineable. The head in question was warped 12 thousands which they would not do. Luckily a friend of mine can straight them out in his BBQ oven with some fixture. 500 degrees F for five hours

Still has to be skimmed afterwards though.
If I were you I would definitely get it skimmed.

Post by **JPM** » 26 Aug 2017, 19:25

I don't know why it failed. There was no single event that I remember. I'll let it go as just plain lots-o-miles and plenty time spent at high rev...

Herman, you lap the valves your self? It doesn't seem difficult, just time consuming. My gasket kit came with their seals, so they certainly need to come out. I might as well make an effort at lapping. What can I use to clean them? some are pretty well caked up. Carb cleaner has little effect.

Sounds like mine is a candidate for a skim. It doesn't seem that expensive. But I'm real tempted to just slap it back together...

OMGBBQ Luckily I don't need to go that far.

Guys, thanks for the encouragement!

Post by **SuperHerman** » 26 Aug 2017, 19:44

Lapping the valves just takes time - it is not difficult. I recommend doing it as the head is off and with those kind of miles it will need it. No special tools needed - just the suction cup stick and some valve lapping paste. I would throw in the special valve stem seal pliers as they are awesome - way better than needle nose.

Cleaning the crud off the valves is not that easy. I used an electric drill and put the valves in the drill to spin them - some use a hose or tape on the valve stem to prevent scratching - I didn't. Then I used a razor blade at an angle to knock off the crud and kept at it until it was pretty clean. I also used this technique on the valve head. The lettering gets in the way but it can be done. After I got it pretty clean I finished off with a green scrotchbrite pad. I stayed away from the area where the valve goes into the valve guide - this will not be dirty anyway. I used a piece of cardboard with holes and numbers to keep the valves in order. It is a long process but not overly complicated - I usually have a sporting event on the TV or the radio on and pause when something actually happens.

Overall just clean everything well - including the deck block and you will be fine.