Been quoted 85 labour to fit 16 valve guides and skim the head,is that reasonable? How much are guides??
skim to make sure its not distorted? surely they skim if it is distorted? according to my bently manual valve guides are just pressed out, pressed back in again and then reamed - no mention of heating the head up in the procedure. there are 2 'special' vw tools for the job.
Pressing out 16v guides is a bit hard, some of the shops I approached wouldn't even do it because either they didn't have the kit to get the angles right, or they had experience of bits of head coming away with the guides.... I was quoted around 90 altogether for the job (excluding skimming but including guides), but ring around - I had prices from over 220! I would get the head surfaced, pressing in the new guides could knock things out of kilter a wee bit. Or you can get the old guides sleeved, which is cheaper and as good if done properly. Or you can get them knurled, which is much cheaper and a great way to wreck guides and valve stems..... Try asking Dave22772727272 or whatever his number is, he should be able to tell you more.
valve guides are 2.50 each x 16= 40+vat 85 quid sounds fair,i think i paid around 90 when i had a 16v heads done,but that was London prices so could be cheaper elsewhere?.
The special "tools" are no more than a piece of angle iron which holds head at correct angle.And as for pressing them out the heat method is the safe choice to avoid making holes oversize but I personally would try it without and use heat if stubborn. Yes you have to ream them out with a hand reamer (7mm)to make sure they run the valves without the hint of sticking. The price you have been quoted sems fair enough and skimming the head is a good way to check for absolute flatness. TSC, 2227 it was
85 doesent sound to bad if thats a all in price.or you could put it towards a gass flowed jobby,you no you want to
Just as a quickie, do you count "skimming" and "surfacing" as different things round your place? I ask for a skim when I want some material taken off, and a surface when I just want to make sure it's flat, taking off the least possible to remove any high areas. Just curious if they are different terminologies over here, or if we all just call it a "skim" on here and know what we all mean.......
Also, I thought you always had to re-cut the valve seats if putting in new guides. I know this opens a bit of a can of worms but what do people think? Joe
Same thing, different way of saying I guess, you only want to remove minimum usually about .005" .Worst one I have seen was about .025" the camshaft must have been like a see-saw on top
Lol.... over here if I ask for a skim they take it that I want some material taken off, to up the CR or whatever. If I ask to have it surfaced they just barely skim the top till it's showing (mostly) bright ally with a few slightly darker patches.... then I attack it with 40 grit paper to give the HG something to key against.....
Makes for a lot more manual valve grinding tho, doesn't it? I have mine recut...... If only I had one of those fancy Serdi machines......
Theres no way of just lapping the valves in after replacing the guides. The factory fitted guides are not finished guides and are bored out to accommodate the correct stem diameter. If you look at the old guides before you remove then you will be able to see that the hole that was bored in them is not central (not easy to see but if you can tell by eye then they cant come close to a finished guide). When you fit the new guide the head should be warmed up (some sort of liquid bath) evenly but only needs to be up to 80-90 degrees and the guides oiled and fitted via a hand press before the head looses too much temperature. If a place says they will have to skim the head because warming will cause the head to distort then give them a wide birth as there doing it wrong of they are full of sh1t. The new guides although they are finished guides will close up (especially on the 16v head) because they are such a tight fit, they can be reamed out (preferably with a fixed reamer) or honed out with a special honing tool. The 8v heads dont always need reaming out because they are an easier fit but you may need to just fit a taper nose reamer down the top of the guide because the top burs over a little by the mandrel used to push in the guide. The seats should always be cut and ask how they will cut them, if they have up to date equipment the will have a Serdi which will cut the seats so accurately that they dont need to be lapped in, they are just vacuum tested to make sure they seal, in fact if you vac test the seal and then lap the valve in with fine paste then the vac test will show up as a fail. 85 to fit the guides and skim it is a little over the top unless they were going to cut the seats as well for that price, if they didnt tell you that the seats needed to be re-cut they must be a bunch of w@nkers. To have guides fitted is usually 2.00 to 4.00 each depending if they supply them or not, a skim between 18-25 depending if its a flat head of an angled head (r/c surface parallel to the head face of not), seats cutting is about 1.25 to 2.50 each depending of what the use to cut them (Serdis are about 20k so the charge a little more) Sorry if Ive put anyone to sleep.
Daz - Is there someone local to you that does them properly? I got the quote from the guys we use at work, but after they bent a Passat 20v cam somehow so it wouldn't turn, I've lost faith in them,they can skim heads ok tho, never had a problem with that
90 is good. Do not let them do it if they are not pressing them into a hot head. Aluminium expands more than bronze alloy, quite easy for your whole guide to move in the bore when very hot if it is just pressed in. Trust me. When you press rock hard bronze alloy into a soft aluminium head the guide reams the inner bore creating a larger hole. Heat the head up on after this and they can drop out if you hold it upside down!! imagine that at 7100 revs and 97 degrees!
