[Saam]

so who wants me to do a tech writeup with lots of pics when i do this ???

[jamienoble]

yeah for sure

[Lokidog]

Are you doing your your own rebuild or are you just taking off the head to be given to a head reconditioner/rebuilder?

What are the reasons for the rebuild ie, oil in water, worn valves?

If oil is getting in to your coolant system or vice versa, your head could be warped and will need to be 'decked' (machined flat again) to regain the water tight seal when replaced back on to your block. Obviously with worn valves they need to be repaired as well (valve seats fixed etc).

I guess I'm asking whether your going to have your head completely rebuilt by professionals. If this is the case, you may want to ask the question… 'If you're doing the work replacing your head back on to your engine will it affect any warranty they may give you'.

It's great to see you're keen to do your own rebuild… But taking your head off and rebuilding it can be quite involved. Good luck with the rebuild anyway!

[datso]

definitely will be a good thing!!! Ive looked into doing polyquad modifications to get more down low from 16v but having trouble finding bigger valves.

Polyquad head mods

[Saam]

Lokidog wrote:

Are you doing your your own rebuild or are you just taking off the head to be given to a head reconditioner/rebuilder?

What are the reasons for the rebuild ie, oil in water, worn valves?

If oil is getting in to your coolant system or vice versa, your head could be warped and will need to be 'decked' (machined flat again) to regain the water tight seal when replaced back on to your block. Obviously with worn valves they need to be repaired as well (valve seats fixed etc).

I guess I'm asking whether your going to have your head completely rebuilt by professionals. If this is the case, you may want to ask the question… 'If you're doing the work replacing your head back on to your engine will it affect any warranty they may give you'.

It's great to see you're keen to do your own rebuild… But taking your head off and rebuilding it can be quite involved. Good luck with the rebuild anyway!

UMMMM i have done a few rebuilds myself already on 8 valve heads and what not, ive got all the tools and whatever the only reason i am doing it is valve stem seals are gone and i am still really tossing up if i should even bother changing them. BUT i am definitely doing the timing belt in a few thousand kays, i will see how i feel then.

sam

[blingdup]

I hate to be the bearer of bad news, but being a mechanic ive learnt to get use to it. If your g13bb jimny engine is showing symptoms of worn valve stem seals, there is a better chance than not, that it will be more to do with worn valve guides and/or valve stems, therefore needing a full head service.
The 16valve head will require more specialized tools than an 8valve head to remove the valves and the guides are the most stubborn ive ever come across, not to mention the heads are prone to cracking.
Basically these things can be a nightmare to repair.
I hope im wrong and wish you all the best, but im just preparing you because ive done quite a few

[datso]

blingdup wrote:

I hate to be the bearer of bad news, but being a mechanic ive learnt to get use to it. If your g13bb jimny engine is showing symptoms of worn valve stem seals, there is a better chance than not, that it will be more to do with worn valve guides and/or valve stems, therefore needing a full head service.
The 16valve head will require more specialized tools than an 8valve head to remove the valves and the guides are the most stubborn ive ever come across, not to mention the heads are prone to cracking.
Basically these things can be a nightmare to repair.
I hope im wrong and wish you all the best, but im just preparing you because ive done quite a few

Ive seen some older castings with these issues but not the latter ones. Even all the SPFI heads Ive come across are all welded up from factory. However they are a good head for performance sakes once the camshaft is replaced with something that doesnt focus so much on torque and improving emissions with less overlap. The potential is there for these overlooked heads to make the same numbers as Honda D16 sohc 16v with a little cleaning and 1mm larger exhaust valves for boost applications.

[Saam]

datso wrote:

blingdup wrote:

I hate to be the bearer of bad news, but being a mechanic ive learnt to get use to it. If your g13bb jimny engine is showing symptoms of worn valve stem seals, there is a better chance than not, that it will be more to do with worn valve guides and/or valve stems, therefore needing a full head service.
The 16valve head will require more specialized tools than an 8valve head to remove the valves and the guides are the most stubborn ive ever come across, not to mention the heads are prone to cracking.
Basically these things can be a nightmare to repair.
I hope im wrong and wish you all the best, but im just preparing you because ive done quite a few

Ive seen some older castings with these issues but not the latter ones. Even all the SPFI heads Ive come across are all welded up from factory. However they are a good head for performance sakes once the camshaft is replaced with something that doesnt focus so much on torque and improving emissions with less overlap. The potential is there for these overlooked heads to make the same numbers as Honda D16 sohc 16v with a little cleaning and 1mm larger exhaust valves for boost applications.

I have heard this about the head that they are a pain to rebuild but i couldn't see it being to hard but maybe i am wrong, my theory was the seals had gone hard because it was sitting not running for 6 - 8 months apparently before that it was not smokey on startup at all.

Also i have always wondered if there was a cam available at all or if it would always be a custom situation, if there is a cam around i will just leave it untill after uni and get the head professionally rebuilt with a new cam.

sam

[nandor85]

i dont know these heads but ive done alot of valve stem seals on a ca18dets ect and u can get away with not removing the head 2 replace these by making sure u rotate the engine 2 top dead center and do ya first and 4th then rotate the engine 2 get second and third up and do these 2

we ust 2 slide the lifters off the shaft and cut down a spanner 2 slide under the shaft and slip the circle end of the spanner ova ya valve and tighten down ya shaft so it takes the pressure off the spring then release the clip and loosen off the lifter shaft so the spring comes free, then replace the seal and put the spring back on and do the reverse

u may need 2 get longer bolts 4 that bolt the lifter down o u can get it 2 tread enough b4 the pressure comes on and stop ya fucking ya tread

it may take alot of time doing this but it saves ya having 2 remove the head but shouldnt take ya more than an hour or so once ya get the hang of it

if ya need more info on on doing it this way just give me a pm im not 2 sure weather it would work4 this type of head havent seen 1 myself but i sure tu could do it this way

[Saam]

the way the valves are setup apparently doing it without the head off is pretty much impossible, so says pretty much everyone i have spoken to about this type of motor...

[nandor85]

oh ok thats kool i just thought u might have been able 2 do it this way like i said i havent seen 1 of these heads so i couldnt say 4 myself if it could work

[blingdup]

If the engine has been sitting for a while it could just be the seals have gone hard, but you should check guide to stem clearance aswell or the new seals wont last long at all and you will be stuck with the same issues.
Just be prepared to open a can of worms. Good luck!

[blingdup]

As for performance, this would have to be the last engine I would consider running boost through. I generally stick to bucket and shim type setups when looking for hp. Im sure you have your reasons though Datso?