Author Topic: to rebuild my mech head, or get a reman? (Read 3142 times)

the4ork · « **on:** November 30, 2007, 11:44:17 pm »

so my head has the usual cracks between the valves... a local shop dissassembled the head and told me it was junk... because of the cracks..

so how do i tell for sure if its a junk head?

would it be cheaper for me to just get a reman? i know they all crack between the valves, but the pressed in cups are good, no cracking that i can see, still need to clean all the carbon off them to tell for sure...

im thinking a 7 angle valve job, new guides, already got the guide seals, valves all look good (can i go oversized?) and last if rebuilding my current head should i get new lifters or just throw the old ones back in and shim them up?

ilomax · « **Reply #1 on:** December 01, 2007, 09:11:00 am »

Take it to a shop that knows what they are doing and what they are talking about.

The cracks between the valves is normal.

It's quite easy to rebuild a head, but you do need special tools (Valve spring conpressor, grinder for the valves and seats, tool to get the valve seals out, that kind of stuff).

If you are going everything else new, you might aswell finish the job and get new lifters. If you do reuse em, make sure they go back in the same spot.

ilomax · « **Reply #2 on:** December 01, 2007, 10:20:19 am »

Ohhh yes, I forgot to mention that part about the pressure testing.
Thats why you're the man or woman, I haven't looked at your profile to check.

jimfoo · « **Reply #3 on:** December 01, 2007, 10:27:29 am »

Haven't run into too many women named Andrew, and if I did, I'd walk the other way. :lol:

subsonic · « **Reply #4 on:** December 01, 2007, 11:55:31 am »

You da Girl Andreweena!!!
:lol:

myke_w · « **Reply #5 on:** December 01, 2007, 12:40:26 pm »

"to rebuild my mech head, or get a reman?"

same thing bro, just rebuild yours with a good shop doing the work..

burn_your_money · « **Reply #6 on:** December 01, 2007, 12:55:11 pm »

How wide are the cracks? The general guideline is if you can stick a dime in them they are too wide.

You can't get oversized valves, then you'll really have some serious cracks

the4ork · « **Reply #7 on:** December 03, 2007, 07:45:15 pm »

what are the cracks from? heat/pressure?

im thinking about having the head surface and valve surfaces ceramic coated, will this prevent cracking in the future? (if i have the cracks welded up)

burn_your_money · « **Reply #8 on:** December 03, 2007, 07:46:25 pm »

I'm pretty sure it's from the rapid change in temperature between the valves on the intake versus the exhaust stroke but I'm not sure about this.

jtanguay · « **Reply #9 on:** December 03, 2007, 09:33:51 pm »

Quote from: "burn_your_money"

I'm pretty sure it's from the rapid change in temperature between the valves on the intake versus the exhaust stroke but I'm not sure about this.

its probably that and the design. the fact that the pre-cups are in there could also affect it as TDI's don't have these cracks (normally anyways..) they probably decrease the structural integrity by quite a bit.

myke_w · « **Reply #10 on:** December 04, 2007, 01:58:51 pm »

Quote from: "jtanguay"

its probably that and the design. the fact that the pre-cups are in there could also affect it as TDI's don't have these cracks (normally anyways..) they probably decrease the structural integrity by quite a bit.

So in other words they warm and cool slower than the surrounding metal?

I find it really strange that tdi's dont have them too :?