VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: ffgb on March 31, 2010, 06:12:47 pm
-
Every machine shop that I spoke with so far said that they would resurface the head regardless. I explained if the head wasn't warped at all, they all said they would resurface it. I further explained about if the head was warped that resurfacing doesn't exactly fix the problem, that the camshaft would not be straight when installed. Every machine shop said it was standard procedure to resurface and just put a thicker head gasket on and call it good. I need new guides and valves regardless, I am just iffy about them resurfacing the head, especially because they all said they leave the precups in. What gives?
-
What gives is every machine shop you have talked to. I would ship it out before letting them touch what I got, but to each his own. Air cooled engines plus in tiffin ohio if you are looking I recommend.
-
.. and the fact that they all think a thicker headgasket is how you compensate for shaving the head means they really don't understand what you're asking them to do, unfortunately. :'(
It *is* standard practice to resurface the head very very slightly... you need a really really good sealing surface to seal properly at 23:1. Some shops do it with the cups in, others remove the cups... depends on the gear they will be using.
-
This sucks! I want my head rebuilt because it needs it. I am having the bottom end done, just need the top end done. At this point, I am willing to purchase a brand new head or rebuilt head. Any suggestions on good places to buy and at a fair price? I am located in Southern California.
Thanks
-
What type do you have, Hydro or Solid head?
-
If you get the valve seat depth and stem length right afterward, skimming the head doesn't change anything.
This is for TDI, but most of the info applies
http://oldforums.tdiclub.com/showthread.php?t=175661 (http://oldforums.tdiclub.com/showthread.php?t=175661)
I recently sent Frank a TDI head, and was real pleased with how it came back, though I don't think he likes working on IDI.
-
This sucks! I want my head rebuilt because it needs it. I am having the bottom end done, just need the top end done. At this point, I am willing to purchase a brand new head or rebuilt head. Any suggestions on good places to buy and at a fair price? I am located in Southern California.
Thanks
PM sent
-
Well, I am receiving my cylinder head in a couple days. It needed 4 intake valves and 8 valve guides. They will lightly resurface it, just to make a clean surface. They will resurface the head with the precups in. Has anyone run into problems later with the precups left in during the resurfacing?
Thanks
-
Well, I am receiving my cylinder head in a couple days. It needed 4 intake valves and 8 valve guides. They will lightly resurface it, just to make a clean surface. They will resurface the head with the precups in. Has anyone run into problems later with the precups left in during the resurfacing?
Thanks
Make sure they go real slow with the cutter or it'll sorta "rise" over the prechambers while cutting the aluminum and they won't be even with the head anymore.
-
The Head can't be milled with the standard milling machine because of the hard Pre Cup, it has to be done on a grinding machine. Not every Shop has that equipment.
-
Well the machine shop called and said my cylinder head is done and ready to pick up. I asked how much did they had to mill, and they said they had to mill the head more in the middle. Total was 3 passes for a total of 8 thousands of an inch. I don't know what to do. I thought the head was in spec, because they said this was the work that needed to be done. I didn't not know that the head was warped that bad. What do you all think. Total for the work was $275, but I only paid $100 for them to start the work. They finished and I can pay the rest for the cylinder head, but I am totally rebuilding the engine and wonder if I shouldn't take this cylinder and accept it at a loss. Further, they haven't line bored anything.
What should I do? Pay $175 and slap the head on with a thicker head gasket and call it good, or am I asking for problems down the road?
-
Not sure I would worry about 8 thou. That's probably less than the carbon build up on the pistons on disassembly.
Ian
-
I know it's too late now... but Rimco in Santa Ana has been the VW machine shop for some time. They knocked 9 thou off my head, with pre-cups installed and shipped back to me for less than $100. Mine didn't require any additional work and I sent them the head disassembled except for the valves. Also to note - that .009" they took was in addition to the amount removed by another machinist that left the head in worse shape than when I brought it to him. Your .008" is nothing to worry about...
Rimco also checked the cam alignment and it was still in spec...
Chris
-
ffgb-let me tell you what its like to walk a mile in your machinists shoes. Here comes in someone that read all the books -and everything on the internet-and knows everything -ABOUT HIS ONE AND ONLY ENGINE-even though hes never laid a hand on it. While the machinist has rebuilt 5 heads a week-for the last 20 years-seen all the problems come + go-know what to look out for-what needs to be done to have a happy customer that has a working component-knows what has screwed up in the past that has cost him and/or the customer money.
Look around the machine shop-se all that big heavy equipment-you think that stuff is cheap? My boss just bought a new surfacer last week-$18k. (I'm shocked he found a decent one that cheap.) What does your machinist charge to cut a head? $65? Wanna do the math to see how long it takes to pay off the machine? If he didn't know what he was doing-you think he'd be getting the work in?
What happens when the customer has a problem--ANY problem? Call the machinist-HE musta screwed up-regardless of the fact he has no control over the customers abilties-or lack thereof-on their 1st major engine job. Its like blaming the butcher because you burnt the steak.
So the machinist suggests what he KNOWs will offer the best chance of working-to cover his ass AND the customers. Thats what a good business man does.
Last fall I did a head gasket on my Jetta-so I surfaced the head on our old machine. It has both grinding + rotary broach (cutter) I ground it-it took over an hour because of having to go real slow-you need the grinder for the cups-but aluminum doesn't like to grind. It was a pain-it would have a been a money LOSING job if it was a paying gig. (Our new machine has a CBN cutter-I'll be doing my TD head next week to try it out.)
Auto machine work-as much as I like it and many years have devoted to it-is probably the least profitable area of the automotive field-the wrokers dont get rich+ neither does the shop owner.
-
Thank You, I appreciate all the information. Now did you use a 2 notch or 3 notch gasket with all that material removed?
-
I would imagine that the head is flat, so to get the notch you need you would just measure piston protrusion. It was flat from the factory, now it is just .008" closer, but still flat and needs the quench.
-
Yup, head gasket thickness is determined by measuring piston protrusion... shaving the head don't factor into it. ;)
-
cool-thanks
-
I took a 3 holer off-and put a 3 holler back on. Like was said-its the pertrusion.
One reason why a machinist would suggest a thicker gasket is: unless there is a spec for head thickness, (most shops are members of AERA for $800 a year-one of the thing you get is access to "prosis" which list specs for 1000's of engines-sometimes there is listings for min head thickness-sometimes not-there isnt a thickness listed for our engine) is its hard to find a virgin. If you were the original owner,and you KNEW this was the head 1st time off, then it would be plenty safe to cut that .008--but how old is the head? 25 years? Has it been cut before? once? twice? Unsure? So he cut it just a little-but now the valves hit the piston--again it now HIS fault. (BEEN THERE!) So to cover his ass he suggests a thicker gasket-no power would be lost-and both you and he are happy.
-
I take back something i said--there is a thickness spec---5.238 new---min 5.215.
-
So he cut it just a little-but now the valves hit the piston--again it now HIS fault. (BEEN THERE!) So to cover his ass he suggests a thicker gasket-no power would be lost-and both you and he are happy.
Yup... I think that happens quite a bit. The really thorough shop will cut the valve seats (re-sinking, if required) and valve stems by the same amount he's shaved the head... now everything is as the VW God's designed. ;)
-
Is it possible to plug weld (or whatever) the water flange holes in the head, and then have them redrilled and re-threaded by a machine shop?
If so, and if anyone has had something like this done by a reputable shop, who/where was the shop?
Not being versed in this, don't know how to shop the job, so one experienced would be nice to know.
TIA
-
So he cut it just a little-but now the valves hit the piston--again it now HIS fault. (BEEN THERE!) So to cover his ass he suggests a thicker gasket-no power would be lost-and both you and he are happy.
Yup... I think that happens quite a bit. The really thorough shop will cut the valve seats (re-sinking, if required) and valve stems by the same amount he's shaved the head... now everything is as the VW God's designed. ;)
VW-describe "really thorough"-is it the machinist does a bunch of work for free-or the "thiefin' jerk at the machine shop that tried to whack me $350 to surface my head?' :-\
BTW-looking at the Prosis for my 82-84 CY motor--it list valve rescession at .040-.060-so you got a plenty safe range.-Mine were .045 before I started. Its probably totally against the rules :-X-but I think i might bring it home + scan it + post up all the specs it lists.
-
Hey Chris, you said Rimco shaved your cylinder head. After all that material was removed, did you see any cracks in your PC's. Did you have any problems later down the road with your PC's. Did them peen them or not? I haven't picked up my head yet. Will do that tuesday. I know it will be nice, clean, and shiny, but should I asked him to peen the PC's if he hasn't?
-
They did not peen the chambers...
It's been a while but I seem to remember at least one crack in the face of one of the chambers which was there before the machine work.
No issues yet and I don't baby the van, other than keeping EGT limited to 1200 degrees.
Rimco didn't make any mention and I didn't think to ask but peening wouldn't hurt things. Stoning the high spots back down could cost a little bit, for the labor involved if you're not up to the task...
Chris
-
Well, the machinist at the shop who rebuilt my head has never peened in the PC's, even though he said he was worried when resurfacing my head because in his experience, he said he had PC's fly from the resurfacing machine because they were knocked loose. I guess I will peen them in myself. Can someone recommend the actual tools used and angles used to peen the PC's? Also, can someone post a pic of a finished peen on the PC's, so I know exactly where to start and finish?
Thank You