Evo Head Service
Jan 20, 2020, 02:23 PM
#1
Newbie
Thread Starter
Evo Head Service
In a year long saga, I've finally identified an intermittent misfire and loss of performance to be related to a leaky valve (cylinder 4 was measured to leak about 40% according to a diagnostic shop) on my head after 90K miles. I am in the process of taking the head off and am going to send it to a local machine shop to have it cleaned and milled, but apart from the obvious replacement parts, I was wondering what exactly I should change out while I have it off.
Obvious:
- Head Gasket
- Timing Chain and Associated Parts
- Valve Cover Gasket
- Head Studs
Questioning:
- Valves
- Valve Stems
- Valve Guides
- Valve Springs
- Valve Locks
- Valve Seals
- Am I missing anything?
My current plan/hope was that I leave the cam shaft on the head while it goes out for repair, but do general machine shops inspect and make suggestions on replacing the parts under "questioning"? Are there some parts which just wear out quickly and it's worth replacing for the cost? Are any of these parts likely to need replacing given the original issue?
Also, it seems that the head studs for OEM are hard to find, and aftermarket ones looks a little different than I was expecting. Anyone have any experience with these or suggestions about what to use instead? https://www.maperformance.com/collec...hi-evo-x-4b11t
For context, my car is not altered in any significant way, with OEM Turbo/Block/Head/etc...
Obvious:
- Head Gasket
- Timing Chain and Associated Parts
- Valve Cover Gasket
- Head Studs
Questioning:
- Valves
- Valve Stems
- Valve Guides
- Valve Springs
- Valve Locks
- Valve Seals
- Am I missing anything?
My current plan/hope was that I leave the cam shaft on the head while it goes out for repair, but do general machine shops inspect and make suggestions on replacing the parts under "questioning"? Are there some parts which just wear out quickly and it's worth replacing for the cost? Are any of these parts likely to need replacing given the original issue?
Also, it seems that the head studs for OEM are hard to find, and aftermarket ones looks a little different than I was expecting. Anyone have any experience with these or suggestions about what to use instead? https://www.maperformance.com/collec...hi-evo-x-4b11t
For context, my car is not altered in any significant way, with OEM Turbo/Block/Head/etc...
Last edited by kyleegbert; Jan 20, 2020 at 02:35 PM.
Jan 20, 2020, 02:42 PM
#2
EvoM Guru
iTrader: (1)
Factory head fasteners are bolts, aftermarket is studs. That's why they look different.
I would ship the head out to HeadGames to be done.
After the valve job is done, lash will need to be set as well. So yes, the cams need to go to the machine shop with the head. You do need to remove them though or you'll risk bending the open valves in transit. You'll also need to remove and identify the buckets (out in marked plastic bags) from the top of the valves because they fall out once the cams are removed. Be sure the cam caps are put back onto the journal they came from.
As far as replacement parts, everything can be measured and inspected and a good machine shop can/should/will make appropriate replacement recommendations.
I would ship the head out to HeadGames to be done.
After the valve job is done, lash will need to be set as well. So yes, the cams need to go to the machine shop with the head. You do need to remove them though or you'll risk bending the open valves in transit. You'll also need to remove and identify the buckets (out in marked plastic bags) from the top of the valves because they fall out once the cams are removed. Be sure the cam caps are put back onto the journal they came from.
As far as replacement parts, everything can be measured and inspected and a good machine shop can/should/will make appropriate replacement recommendations.
The following users liked this post:
kyleegbert (Jan 21, 2020)
Thread
Thread Starter
Forum
Replies
Last Post