Nooooooo Vanny not in a drill, just the suction cup and some time, get the thing checked for flatness too, you wouldnt want to put it on and have the water come shooting out of the sides, and whats all this about a thinner gasket lowering the compression???[:)]
Stewart
Engine rebuilding
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vanny
- Posts: 767
- Joined: 16 May 2002, 21:08
- x 1
think you must have got a dose of radiation to the head stewart, THICKER gasket!
I was intending on sticking the suction cup stick in the drill rather than magically attaching the valve though! BUt i'll be patient and do it manually, gonna get the special book out and read the grinding in chapter in a minute, pretty good book just pretty old!
I dont understand this whole cutting a face thing. The valve guide is just a brass pipe with a hole in the middle right? so what about it needs cutting in?
I figure while it's with the nice man, i will get him to check it for flatness etc and if it needs it them skim it, but i'd rather not, just seems like a ducktape sort of bodge!
I was intending on sticking the suction cup stick in the drill rather than magically attaching the valve though! BUt i'll be patient and do it manually, gonna get the special book out and read the grinding in chapter in a minute, pretty good book just pretty old!
I dont understand this whole cutting a face thing. The valve guide is just a brass pipe with a hole in the middle right? so what about it needs cutting in?
I figure while it's with the nice man, i will get him to check it for flatness etc and if it needs it them skim it, but i'd rather not, just seems like a ducktape sort of bodge!
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tomsheppard
- Posts: 1802
- Joined: 19 Dec 2002, 14:46
- x 1
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James.UK
- Posts: 1169
- Joined: 14 Dec 2003, 23:12
- x 2
In days long gone we used to use a small sheet of glass to check for flatness.. I have actually lapped heads with a pane of glass and fine grinding paste, it worked fine. Sheet glass is normaly very very flat.
[:)]
Procedure:- put some engineers blue on the glass and place the head on it, then move the head about in a circular movement, turn it over and any high spots will be coloured blue, wipe the blue off, put some fine grinding paste on the glass and slide the head around on it for a while, then check again untill the head is flat.. Make sure you clean the head thoroughly afterwards as you dont want grinding paste in any moving parts! [:0] [:(!]
A new valve guide is pressed in and then reamed to size normaly, no additional work needed. The bits you have to 'cut' are the areas where the valve face forms a seal with the face in the head. Lapping with a dolly and grinding paste is the normal way to do it..
Procedure:- With the handle of the dolly between the palms of your hands rotate it first one way then the other, move the valve round a bit after a few goes so the valve face gets ground evenly all round, and not just in one spot.. [8)]
Using a drill will make circular grooves-scratches right round the seat faces and is not a good idea. [V]
.
[:)]
Procedure:- put some engineers blue on the glass and place the head on it, then move the head about in a circular movement, turn it over and any high spots will be coloured blue, wipe the blue off, put some fine grinding paste on the glass and slide the head around on it for a while, then check again untill the head is flat.. Make sure you clean the head thoroughly afterwards as you dont want grinding paste in any moving parts! [:0] [:(!]
A new valve guide is pressed in and then reamed to size normaly, no additional work needed. The bits you have to 'cut' are the areas where the valve face forms a seal with the face in the head. Lapping with a dolly and grinding paste is the normal way to do it..
Procedure:- With the handle of the dolly between the palms of your hands rotate it first one way then the other, move the valve round a bit after a few goes so the valve face gets ground evenly all round, and not just in one spot.. [8)]
Using a drill will make circular grooves-scratches right round the seat faces and is not a good idea. [V]
.
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Kowalski
- Posts: 2557
- Joined: 15 Oct 2003, 17:41
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fastandfurryous
- Posts: 1389
- Joined: 07 Jul 2004, 17:57
- x 4
Putting a thicker gasket in a turbo engine to reduce compression and run more boost is very much a petrol engine procedure. It's done to reduce the volatility of the mixture so that you don't get pre-ignition, and can run more ignition advance.
On a diesel engine, this is all irrelevant, as you are only compressing fresh air.
I believe the XUDT engine has a lower compression ratio than the XUD only because the pre-combustion chambers are larger. I've built a 1.9TD engine with 23:1 compression ratio, and over 20psi of boost in the past, and it was both reliable, and went like the clappers. (a 405 TD estate that out-accelerated a Ford XR3i!)
On a diesel engine, this is all irrelevant, as you are only compressing fresh air.
I believe the XUDT engine has a lower compression ratio than the XUD only because the pre-combustion chambers are larger. I've built a 1.9TD engine with 23:1 compression ratio, and over 20psi of boost in the past, and it was both reliable, and went like the clappers. (a 405 TD estate that out-accelerated a Ford XR3i!)
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fastandfurryous
- Posts: 1389
- Joined: 07 Jul 2004, 17:57
- x 4
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by vanny</i>
i appreciate the valves will be hardened, but surely the head alloy is soft enough to be ground out? I was thinking i might just attach the valve to a drill, lob some paste on it and off i go at a low speed!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Actually, The valve doesn't seal against the soft alloy of the head, the head has hardened steel inserts in it. Your best bet is coarse grinding paste, a suction cup, and a lot of patience. Then fine grinding paste, and even more patience.
I have used a drill to grind in valves before, but it makes a bloody awful mess (circular grooves in the seat) and wasn't any faster anyway.
i appreciate the valves will be hardened, but surely the head alloy is soft enough to be ground out? I was thinking i might just attach the valve to a drill, lob some paste on it and off i go at a low speed!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Actually, The valve doesn't seal against the soft alloy of the head, the head has hardened steel inserts in it. Your best bet is coarse grinding paste, a suction cup, and a lot of patience. Then fine grinding paste, and even more patience.
I have used a drill to grind in valves before, but it makes a bloody awful mess (circular grooves in the seat) and wasn't any faster anyway.
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dnsey
- Posts: 1538
- Joined: 20 Oct 2004, 01:39
- x 19
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alan s
- RIP 2010
- Posts: 2542
- Joined: 26 Jan 2001, 15:53
- x 6
Vanny, mayte, waddya doin' to yourself?
Without upsetting all and sundry, me listening to you is like me looking in a mirror several years ago before I got older and wiser and had my bum burnt a few times.
All of these makeshift methods are possible and most I have employed with varying degrees of success over the years when I've had things go pearshaped when it was the 23rd of December and I needed my car to tow a caravan away for 3 weeks holiday and nobody was open nor going to be for the next 2 to 4 weeks, but at the end of the day, it all ends up having to come apart prematurely and having to be done properly, so instead of it costing "X" pounds (including gaskets and seals) to get it done, it ends up costing "X" pounds including <b>2 sets</b> of gaskets and seals etc plus treble the amount of time plus the inconvenience of not having the car, plus the chance you'll stuff it up and may even get 3 goes at doing it if you're really unlucky.[:(!]
I learnt a long time ago that these jobs need to be done 100% right first time and if this happens, the results are more than a little pleasing.
Find an engine rebuilder and ask for the head to be planed to be sure it's flat; he'll use a surface grinder and it will be true, no ifs, buts or maybe's. That will take him less than a half hour.
Then get him to do a check on the valve guides and if necessary they can shrink a set of those in. If they check out, they can then use a cutting wheel with a guide that fits into the valve guide and cuts the seat at exactly 45 degrees. He can then face the valves, again exactly at 45 degrees so that they mate exactly with the seats already cut. If you feel inclined to lap them in after that, so be it but normally the cutting of the seats and the facing of the valves is sufficient to see a good job. Reassemble, but a "VRS" gasket kit (V alve R egrind S et) reassemble (although your engine man should do this as part of the job, drop the head back on the bottom part and you're finished.
Before you panic at the possible cost, I'd suggest you ask for a quote from a couple of these guys as I think you'll be pleasantly surprised at just how cheap this can be from an honest rebuilder.
Best bit is, you reassemble with full confidence that the H/G won't blow because the face of the head isn't perfectly true, the valves won't leak because you stuffed up on the lapping and the collets won't fall off because you didn't have a decent valve lifter to remove and replace them.
Overall, a good investment; wreck the car for any reason and sell the head with confidence for best price, because it has been professionally rebuilt.
Alan S
Without upsetting all and sundry, me listening to you is like me looking in a mirror several years ago before I got older and wiser and had my bum burnt a few times.
All of these makeshift methods are possible and most I have employed with varying degrees of success over the years when I've had things go pearshaped when it was the 23rd of December and I needed my car to tow a caravan away for 3 weeks holiday and nobody was open nor going to be for the next 2 to 4 weeks, but at the end of the day, it all ends up having to come apart prematurely and having to be done properly, so instead of it costing "X" pounds (including gaskets and seals) to get it done, it ends up costing "X" pounds including <b>2 sets</b> of gaskets and seals etc plus treble the amount of time plus the inconvenience of not having the car, plus the chance you'll stuff it up and may even get 3 goes at doing it if you're really unlucky.[:(!]
I learnt a long time ago that these jobs need to be done 100% right first time and if this happens, the results are more than a little pleasing.
Find an engine rebuilder and ask for the head to be planed to be sure it's flat; he'll use a surface grinder and it will be true, no ifs, buts or maybe's. That will take him less than a half hour.
Then get him to do a check on the valve guides and if necessary they can shrink a set of those in. If they check out, they can then use a cutting wheel with a guide that fits into the valve guide and cuts the seat at exactly 45 degrees. He can then face the valves, again exactly at 45 degrees so that they mate exactly with the seats already cut. If you feel inclined to lap them in after that, so be it but normally the cutting of the seats and the facing of the valves is sufficient to see a good job. Reassemble, but a "VRS" gasket kit (V alve R egrind S et) reassemble (although your engine man should do this as part of the job, drop the head back on the bottom part and you're finished.
Before you panic at the possible cost, I'd suggest you ask for a quote from a couple of these guys as I think you'll be pleasantly surprised at just how cheap this can be from an honest rebuilder.
Best bit is, you reassemble with full confidence that the H/G won't blow because the face of the head isn't perfectly true, the valves won't leak because you stuffed up on the lapping and the collets won't fall off because you didn't have a decent valve lifter to remove and replace them.
Overall, a good investment; wreck the car for any reason and sell the head with confidence for best price, because it has been professionally rebuilt.
Alan S
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bxbodger
- Posts: 1455
- Joined: 23 May 2003, 03:34
- x 1
Alan is correct of course-I've been there as well many years ago with a shot BL A series head!! The thing burned an exhaust valve out, with all the attendant smoke on start up, etc, so off with its head, new valve, lap the seats in and stick new stem seals on for good measure, back on the car, and, of course, another burned exhaust valve in a week or so!!
I didn't learn, and just put in yet another valve!!! Head off twice now, two lots of gaskets, etc........luckily an A series head off job can be done in 30 minutes.....
In the end I gave up and took the head down to a proper engineer, who skimmed it and put new valve seats in, which, of course, is what I should have had done in the first place-It cost money but not a lot more than what I had already thrown at gasket sets, valves, etc!! I should have realised that no amount of valve lapping was going to put a recessed valve seat right!!!
With modern oils and fuels making carbon a thing of the past the sucker stick and valve paste should really be consigned to history: they were only ever useful for removing carbon and there really is no need for them now- as the saying goes, you can't make a silk purse out of a sows ear!!!
Give it up Vanny-cut your losses and take it to a pro!!!!!!!!
I didn't learn, and just put in yet another valve!!! Head off twice now, two lots of gaskets, etc........luckily an A series head off job can be done in 30 minutes.....
In the end I gave up and took the head down to a proper engineer, who skimmed it and put new valve seats in, which, of course, is what I should have had done in the first place-It cost money but not a lot more than what I had already thrown at gasket sets, valves, etc!! I should have realised that no amount of valve lapping was going to put a recessed valve seat right!!!
With modern oils and fuels making carbon a thing of the past the sucker stick and valve paste should really be consigned to history: they were only ever useful for removing carbon and there really is no need for them now- as the saying goes, you can't make a silk purse out of a sows ear!!!
Give it up Vanny-cut your losses and take it to a pro!!!!!!!!
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alan s
- RIP 2010
- Posts: 2542
- Joined: 26 Jan 2001, 15:53
- x 6
Taking this to more detail; I once spent a couple of weekends working on a head doing it all by hand. I reassembled and it blew a gasket; it wasn't perfectly flat. I removed spent more time and got it right. Off again and found a concave valve. Relapped and reassembled and something else went haywire. I had use of a workshop of a dealership owned by a mate's father. One Saturday whilst working on the head (again) the foreman came in to do a job for himself, took one look at what I was trying to do, told me in no uncertain terms I'd eventually throw it away in disgust because it would never work properly, walked into the machine shop and in under an hour I had a fully redone head. Refitted, went like a charm and no more problems.
Here's a few potential problems that can happen:
Checking head for flatness; edges get rounded due to sheer size and weight when trying to lap by hand.
Valves will get concaved giving the ability for sealing properly to be reduced and leading to lessening of compression due to leakeage. Concave valves and ridged seats affect the gas flow and instead of gas passing over a nice smooth track (the idea of polishing ports prior to reaching the valve area) it's like driving over a corrugated dirt track; rough and messes up gas flow pattern.
A hard high spot on a seat will become a groove in a valve when the valve is seated particularly if mechanical means are used, such as a drill and will cause total compression lost = to a burnt out valve.
Fine tracks in the valve seat will not be seen if hand machined but will be evident if the correct tool is used to cut it.
Labourwise from the machine shop should not exceed 1 1/2 hours to do the lot; I've dropped them into machine shops in years gone by and gone up the street and done a bit of shopping nad come back and collected, but in any case, a common way to quote is for the "plane to check trueness" plus a price per valve for facing and one per seat for cutting. If they're required to strip, clean and reassemble that can be more and often they can't quote on that due to it being an unknown commodity, but if you offer to DIY, ask what he expects in matters such as keeping all the components marked so they go back where they come from although done as I suggest, this no longer becomes critical unless there's some bodge work there from previously.
Alan S
Here's a few potential problems that can happen:
Checking head for flatness; edges get rounded due to sheer size and weight when trying to lap by hand.
Valves will get concaved giving the ability for sealing properly to be reduced and leading to lessening of compression due to leakeage. Concave valves and ridged seats affect the gas flow and instead of gas passing over a nice smooth track (the idea of polishing ports prior to reaching the valve area) it's like driving over a corrugated dirt track; rough and messes up gas flow pattern.
A hard high spot on a seat will become a groove in a valve when the valve is seated particularly if mechanical means are used, such as a drill and will cause total compression lost = to a burnt out valve.
Fine tracks in the valve seat will not be seen if hand machined but will be evident if the correct tool is used to cut it.
Labourwise from the machine shop should not exceed 1 1/2 hours to do the lot; I've dropped them into machine shops in years gone by and gone up the street and done a bit of shopping nad come back and collected, but in any case, a common way to quote is for the "plane to check trueness" plus a price per valve for facing and one per seat for cutting. If they're required to strip, clean and reassemble that can be more and often they can't quote on that due to it being an unknown commodity, but if you offer to DIY, ask what he expects in matters such as keeping all the components marked so they go back where they come from although done as I suggest, this no longer becomes critical unless there's some bodge work there from previously.
Alan S
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vanny
- Posts: 767
- Joined: 16 May 2002, 21:08
- x 1
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G4EIY
- Posts: 186
- Joined: 04 Jun 2003, 18:20
Thermostat Testing
If you do not replace the thermostat, then check the original one by lowering it into a kettle, then bring the water to the boil. When the stat opens, remove quickly and measure the ammount it opens.
A new one should open about 8mm.
If it's 5mm or below I would replace it.
Cheers and good luck
If you do not replace the thermostat, then check the original one by lowering it into a kettle, then bring the water to the boil. When the stat opens, remove quickly and measure the ammount it opens.
A new one should open about 8mm.
If it's 5mm or below I would replace it.
Cheers and good luck
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vanny
- Posts: 767
- Joined: 16 May 2002, 21:08
- x 1
USefull to have some actual measurements to guide by Brian, thanks. I think there is a damn good probability that i will change the thermostat and probably the water pump along with the belt. The belt and pump have less than 10k miles on them but i figure if a jobs worth doing!
Have spoken to the lovely people at Mersey Engines today and they've said its gonna be £200 all in to rebuild the head including reshimming etc and as an added extra that includes the gasket and bolts! I figure it would cost me around £80 ish in parts anyways. Gonna save up some extra pennies then call them and find out exactly what there gonna do, seal by seal!
Whats people think of the price? Sounds like a lot to me but taking on advice of people here its probably money well spent!
Have spoken to the lovely people at Mersey Engines today and they've said its gonna be £200 all in to rebuild the head including reshimming etc and as an added extra that includes the gasket and bolts! I figure it would cost me around £80 ish in parts anyways. Gonna save up some extra pennies then call them and find out exactly what there gonna do, seal by seal!
Whats people think of the price? Sounds like a lot to me but taking on advice of people here its probably money well spent!
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alan s
- RIP 2010
- Posts: 2542
- Joined: 26 Jan 2001, 15:53
- x 6
I did a CX head about 3 years back. That was cut seats, face valves supply and fit valve guides, gaskets and seals for the top end only, plane head for flatness, fill in corrosion on alloy head with weld, clean up and pressure test and it worked out to around A$500 so for a full job on a diesel, I'd say that was a pretty line ball price; I'd have no problems with it.
Alan S
P.S. Currency conversion:
500.00 AUD
Australia Dollars = 215.966 GBP United Kingdom Pounds
Alan S
P.S. Currency conversion:
500.00 AUD
Australia Dollars = 215.966 GBP United Kingdom Pounds