+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Tuning (https://www.superturbodiesel.com/std/forumdisplay.php?fid=6)
+--- Forum: Engine (https://www.superturbodiesel.com/std/forumdisplay.php?fid=7)
+--- Thread: Headgasket fix (/showthread.php?tid=4581)
Headgasket fix - MFSuper90 - 05-15-2013
So I am getting ready to fix the HG on my om617. I am going to order HG kit, offset woodruff key, and timing chain tension spring.
Is there anything else I should replace while I am pulling the head off? I'd like to get it ordered before I pull the head.
RE: Headgasket fix - Duncansport - 05-16-2013
(05-15-2013, 09:45 PM)MFSuper90 So I am getting ready to fix the HG on my om617. I am going to order HG kit, offset woodruff key, and timing chain tension spring.
Is there anything else I should replace while I am pulling the head off? I'd like to get it ordered before I pull the head.
Years ago when this engine was around a bit more, head gasket jobs usually also resulted in valve guides and exhaust valves, stem seals. We always rolled in a new timing chain as well.
Just my $.02
RE: Headgasket fix - Simpler=Better - 05-16-2013
Your exhaust guides are definitely worn, intake may or may not be-measuring them is easy.
While the head is off I'd at least clean up the ports and ream the prechambers or swap in 1985 PCs.
Don't forget to refresh the timing chain guides while she's out it's much easier.
Side note, it is very possible to pull the head without breaking the timing chain
RE: Headgasket fix - MFSuper90 - 05-16-2013
I checked timing chain stretch, and its only off two degrees, So i figure I will just put the offset key in for now.
I am definitely gonna have the head checked, plane it if need be, and make sure all guides and seals are in good condition.
Simpler, can you elaborate?
So i need to add guides (probably), chain guides and seals to the list.
Thanks fellas
RE: Headgasket fix - Simpler=Better - 05-16-2013
People will argue with me on this but the head has a bunch of casting defects. It's A-OK for plodding along at 120hp for a million miles, but if you want to get more then you better "port" the intake and exhaust passages. I did a slapchop job on mine, but it will definitely make a difference. JTY did his when it was off too. Port your manifolds while it's disassembled too.
up to 84 the prechambers have small passages, the 85 has larger ones and more HP. Some people have reamed them out to get more power, OM616 has a thread on it here. No dyno proof, but if it's enough to feel it then that's good enough for me.
Don't deck the head unless you absolutely have to-if you take any material off you will need to screw around with spacers under the prechambers to prevent a piston strike.
valve seals are cheap, measure your old ones and see if you can get high performance ones in the same size. many cars use the same valve stem diameter and base diameter etc. Just a thought.
exhaust guides always wear out first. any shop can measure them, or just buy some snap gauges
While my head was off I poured a couple bottles of MMO on top of the cylinders, letting it soak past over the course of a few days. This supposedly helps free up rings, Kroil also has a specialty product. I have no documented proof that it does anything, but if made me feel warm and fuzzy inside.
RE: Headgasket fix - MFSuper90 - 05-16-2013
(05-16-2013, 12:14 PM)Simpler=Better People will argue with me on this but the head has a bunch of casting defects. It's A-OK for plodding along at 120hp for a million miles, but if you want to get more then you better "port" the intake and exhaust passages. I did a slapchop job on mine, but it will definitely make a difference. JTY did his when it was off too. Port your manifolds while it's disassembled too.
up to 84 the prechambers have small passages, the 85 has larger ones and more HP. Some people have reamed them out to get more power, OM616 has a thread on it here. No dyno proof, but if it's enough to feel it then that's good enough for me.
Don't deck the head unless you absolutely have to-if you take any material off you will need to screw around with spacers under the prechambers to prevent a piston strike.
valve seals are cheap, measure your old ones and see if you can get high performance ones in the same size. many cars use the same valve stem diameter and base diameter etc. Just a thought.
exhaust guides always wear out first. any shop can measure them, or just buy some snap gauges
While my head was off I poured a couple bottles of MMO on top of the cylinders, letting it soak past over the course of a few days. This supposedly helps free up rings, Kroil also has a specialty product. I have no documented proof that it does anything, but if made me feel warm and fuzzy inside.
If they have to take ten thousands off it should be alright, shouldnt it?
Not sure what the clearances are on the PC's
I have a extra set of PC's out as we speak that should be getting the bore enlarged, and i am going to reem them when i get em back.
Depending on my time frame I might do some port and polish. Probably not though since our shop always needs to have something else in it. I am temped to have my extra head redone, then work on it so all i have to do is slap it back together.
What were you saying about pulling the head off without breaking the chain?
RE: Headgasket fix - Simpler=Better - 05-16-2013
A couple ten thou shouldn't be too bad, somewhere on PP there is a list of the clearances
Set it all to 24* BTDC or 26*BTDC. Take the cam gear off, tie a string around the timing chain, and lower it into the abyss. When you reassemble make sure everything is where it should be and you're golden. I had my chain down in the abyss and turned the engine over, etc. Just be careful with your timing marks when you reassemble and time it.
RE: Headgasket fix - SurfRodder - 05-17-2013
I spoke with a guy a few weeks back at a local part yard that has been working on these things since they were new and he told be that shaving a bit off the head can cause a nice increase in HP... If you want, Ill try to find his phone number and get specifics on how much to shave off... that would be nice info to post here anyway, so when Ill try to remember to call him anyway. I'd think it couldn't be too much due to the aforementioned clearance issue...
RE: Headgasket fix - MFSuper90 - 05-17-2013
Hmm. By shaving the head it would cause an increase in compression ratio. Interesting that even more compression would help!
Thinking about a DYI port and polish job, but I don't currently know enough about it to try it. Can anyone school me on a little head work?
RE: Headgasket fix - willbhere4u - 05-17-2013
The heads is flat decking It will not increase the compression. unless you use a thinner gasket or don't re shim the prechambers when your done
RE: Headgasket fix - MFSuper90 - 05-17-2013
(05-17-2013, 04:21 PM)willbhere4u The heads is flat decking It will not increase the compression. unless you use a thinner gasket or don't re shim the prechambers when your done
Dohhh. Musta had a brain fart
RE: Headgasket fix - SurfRodder - 05-18-2013
(05-17-2013, 04:21 PM)willbhere4u don't re shim the prechambers when your doneThis is what I believe he was talking about.... not sure how much you could get away with tho...
(05-17-2013, 04:21 PM)willbhere4u don't re shim the prechambers when your doneThis is what I believe he was talking about.... not sure how much you could get away with tho...