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Post by stantondavies on Nov 25, 2015 23:25:24 GMT
The search facility has gone awol for the time being so I don't know if this is answered elsewhere. Is it really necessary to remove the front and rear rocker shafts as it says in the workshop manual in order to extract the exhaust valves?
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Post by djm16 on Nov 26, 2015 2:18:23 GMT
If we are talking about a 3 litre, then no.
You would do well to buy or borrow a valve seat cutter if the head has not been off for 100k or more. The seats may well be pitted beyond lapping.
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Post by Phil Nottingham on Nov 26, 2015 18:34:36 GMT
Absolutely not but you may find the seats need replacing/recutting and ordinary steel cutters are not hard enough. NOT ON SEARCH ANYWAY Why remove the valves?
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Post by stantondavies on Nov 26, 2015 22:44:28 GMT
Car misfiring so checked compression which was low on cylinders five and six and a little bit down on three.
Have removed the exhaust valves and after 151,000 miles they clearly need replacing. No.5 has a chunk missing off the face. Two aren't true. Very little play to none in the guides, the small amount of wear is probably on the valve stems.
Rover exhaust valves are numbered 512140. Are these the same as the Landrover 2.6 series 2 & 3? JRW wants £21.60 a valve which is about double what I was expecting.
Don't understand why the manual prescribes so much unnecessary dismantling. Rover allowed 6.5 hours to remove and replace one valve.
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Post by Phil Nottingham on Nov 26, 2015 23:20:09 GMT
Wadhams are better quality and will run lead-free as your RoVeR valves would have. The LR are likely to be cheap and will be for 2.6L pre-Westlake head. Check seat have no major cracks/pits
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Post by Warwick on Nov 27, 2015 1:44:34 GMT
.... Rover allowed 6.5 hours to remove and replace one valve. Is it an original Rover workshop manual, or a later revised version from the Leyland era? It might include lunch as well as morning and afternoon tea breaks.
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Post by djm16 on Nov 27, 2015 1:49:56 GMT
If you are friendly with a workshop, you might take them the valves and see if they can be trued up. If you are very lucky they may lend you a valve seat cutter too (toothed cutter, grinding wheels - with angle setting device).
I have done this three times now with different cars. The most recent one a lot better than the first!
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Post by stantondavies on Nov 28, 2015 21:17:44 GMT
.... Rover allowed 6.5 hours to remove and replace one valve. Is it an original Rover workshop manual, or a later revised version from the Leyland era? It might include lunch as well as morning and afternoon tea breaks. See the attached for the source document. The time will include taking the head off.
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Post by stantondavies on Nov 28, 2015 22:06:32 GMT
If you are friendly with a workshop, you might take them the valves and see if they can be trued up...... I am lucky that I have a friend in the trade and I take the car to his workshop, where it now is. He has the kit to deal with the valves. I attach photographs including No 6 valve which has been in the valve facer and shows that it is not straight, No 5 valve which has a chunk missing and the block showing cylinders 5&6 where the compression readings were low.
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Post by Phil Nottingham on Nov 28, 2015 22:33:46 GMT
Not good = old age really catching up?
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Post by stantondavies on Nov 28, 2015 22:51:32 GMT
Not good = old age really catching up? Is that me or the car your talking about, Phil? Car has done 151k so have to expect some deterioration!
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Post by enigmas on Nov 29, 2015 2:14:27 GMT
Looks like a lot of labour and expense ahead of you Stanton! Lots of oil residue in the combustion chamber (blowby on the exhaust side) The valve also appears not to have been rotating or seating concentrically as illustrated by the wear on half its sealing face. The exhaust guides are probably well worn too and since they're in the block it's going to be a pig of job! Good luck with the rebuild.
As an aside, what type and viscosity oil are you using in the engine?
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Post by stantondavies on Dec 2, 2015 0:13:10 GMT
........The exhaust guides are probably........ ......what type and viscosity oil are you using in the engine? Guides are showing minimal to no wear at all - some of the detectable wear will be on the valve stems. I am using Halfords Classic oil, 20W/50.
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Post by enigmas on Dec 2, 2015 10:40:46 GMT
Not trying to unsettle you Stanton, but being realistic on an engine of that age, unless it has been rebuilt, how could the exhaust guides show minimal to no wear at all? Usually the valve material is harder than the guide. The guide provides the lubricating medium between the 2 surfaces. Another factor is that a byproduct of combustion in an IC engine is carbon. Carbon build up is evident on the exhaust valves and is unfortunately, a very effective abrasive. If using hydrocarbon based fuels this is an issue for any IC engine. If there's oil on the exhaust valve heads it's either being transferred there by piston/cyl blow by, or being pulled down the inlet guides during the intake stroke. So how are the inlet guides and their respective stem seals? I'd also want to find out why the exhaust valves aren't rotating during operation. (One side illustrates blowby/scorching...the valve head is not seating concentrically.) The explanation and requirements for valve rotation are outlined in the link below if you have a technical interest? Valve Rotation
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Post by djm16 on Dec 2, 2015 13:35:33 GMT
The three bores visible in you bottom photo only show carbon deposition, no obvious oil. Moreover there appear to be extensive honing marks in the bores. Has it had new rings fitted recently?
I do not think you will lose much by replacing the exhaust valves and re-cutting the seats. You might even get another 20,000 miles before an engine rebuild becomes more urgent.
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Post by Phil Nottingham on Dec 2, 2015 19:05:17 GMT
It does depend what use the car is going to be put to I do not really want mine to outlast me
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Post by enigmas on Dec 2, 2015 21:03:25 GMT
It does depend what use the car is going to be put to I do not really want mine to outlast me Phil I don't know too many enthusiasts who are genuinely passionate about (their) classic car(s) or related types of vehicles who are into band-aid repairs or expedient fixes to make them last over the short time. I can imagine this type of policy in a young man (general impatience) or an individual who can't focus, but most owners of these types of vehicles have an obsessional of pride in their car and in any work being done on them. It's not always or doesn't have to be about the money, but about the attention/care in putting a component, either new or used together.
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Post by djm16 on Dec 2, 2015 21:27:20 GMT
Enigmas, I do feel you might be just a little unfair. Minor engine repairs (fixes, bodges - whatever you prefer to call them) such as new rings, refacing valves and valve seat, replacing big end bearing shells (without grinding the crank) are all perfectly acceptable, although not as definitive as a full engine rebuild.
Pros: A full engine rebuild may result in an "as new" engine that needs no further attention for 100,000 miles. Cons: The cost is to some people astronomical. At a rough guess, an engine out, crank grind, rebore, head skim, valve and guide replacement, camshaft and bearing replacement, welsh plugs and the rest are going to set you back around £10,000 if you have to pay someone to do it. A full engine rebuild shortens the overall life of an engine. After all, there are only so many rebores and cranks regrinds permitted.
In contrast, most of us amateurs started out by doing things ourselves that are manageable and within our limited budget. Rings and valves fall into that category.
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Post by enigmas on Dec 2, 2015 22:14:08 GMT
DJM16 your reading more into my comment than was intended. I'm into recycling, renovating and repairing components. It's not the money you spend, it's how something is assessed and then how the repair/fix is done. Take another look at the valve head, that carbon layer didn't just magically build up. The cyls...I can't tell clearly as the photos are poor quality but if the honing is purely radial...looks really coarse to me, that's not good either! I'm just making comment on what I'm seeing...not trying to devastate anyone.
Posting anything to a public forum will elicit responses...good, bad and indifferent. It's an element of social commentary. None of us who post our views or work are immune from it either. The safest option is to not post anything at all and become a passive observer. That's a personal choice.
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Post by stantondavies on Dec 6, 2015 17:31:22 GMT
......... being realistic on an engine of that age, unless it has been rebuilt, how could the exhaust guides show minimal to no wear at all? ............ I'd also want to find out why the exhaust valves aren't rotating during operation. (One side illustrates blowby/scorching...the valve head is not seating concentrically.) The engine was rebuilt at 70,000 and has covered another 81,000 miles. I have re-ringed the pistons as the engine has overheated thanks to catastrophic water loss when the hose came off the rear heater piping. This was courtesy of "professional" mechanics not tightening the clip adequately and the hose vibrating off over time. Having had a corneal transplant my eyesight is much improved and I can see to do work myself again. I am an amateur mechanic and had not honed bores with a honing machine before, previously I'd done this by hand. So apologies for the result! The valves on cylinders five and six are bent probably by the overheating, that is why there is carbon on one side of the face as the valve facing machine was catching only one side of the valve before I stopped.
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Post by enigmas on Dec 7, 2015 1:32:59 GMT
Stanton congratulations on the work you've undertaken... I understand tight budgets and poor quality work done by 'others'...who don't really care!..been there myself. There are options though for restoring components, as was done in the past...not everything has to be binned! It's just part of the culture today. When you re-ring the pistons, consider this. The top ring land usually illustrates the most wear. You really don't want more than .004" lateral play otherwise the engine may become an oil pumper, as the ring flutters/oscillates up and down. The top ring can be machined to both widen the groove slightly and square the lands. Then custom top rings can be made (just the top ring for each piston) quite inexpensively (JP pistons...$14 AUD ea. I did a set like this several yrs ago) The lower grooves use a standard ring set; so there's one top ring left remaining in a box set. As for the bores, a very 'light' deglaze is all that's required...nothing more...definitely nothing too vigorous, otherwise it will bell-mouth or open up excessively. A 'light' cross hatch pattern to retain an oil film is all that's required. If the pistons are slightly down on size there are modern high temp coatings available (HPC...at $35 AUD per piston) that will increase the skirt size up to .003" if required. As for the valves. Are you sure the stems are bent. Take a look at the ends of the valves and the exhaust rocker tip where they contact. They usually need refacing due to wear marks/pocketing...especially the rocker tip as the working radius deteriorates over time. This would have a detrimental effect on any valve rotation that was designed into the system. As for valve guide reclamation have a look at these inserts. ( K-Line Valve Guide-Liners) I've had several cyl heads done. They have a good reputation but require a skilled operator to fit them correctly. They'd be a good option if only on the exhaust side as clearances can be kept tight. cylinderheadshop.com/k-line-guide-liners/
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Post by stantondavies on Dec 7, 2015 23:21:43 GMT
Thanks, Vince. When the exhaust valves were rotating in the facing machine a slight oscillation was apparent, also evidenced by the one side of the face down to bare metal while the other side still had carbon on it - see previous photographs. I am investing in a set of new valves (£130 plus carriage).
Turning to the guides, I have tried each valve in its guide to find any wear. Apart from No6 it is difficult to discern any. How would you measure guide wear and what are the acceptable tolerances? It is easy enough to to put a micrometer on the valve stem, but down a valve guide?
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Post by enigmas on Dec 8, 2015 2:08:59 GMT
It's good practise Stanton if you have the funds to fit new exhaust valves as this side is under the most heat related stress. New exhaust valves also won't have a lifetime of heat stress/fatigue. I have a mate (qualified machinist/engine reconditioner) who runs his own business primarily rebuilding cyl heads. He generally fits k-line inserts into cast iron valve guides as he doesn't like the distortion/distress caused to a cyl head or block by the guide removal process...damage to the guide hole. Rebuilding a cyl head...having the guides and valves correctly fitted to tolerance, etc...really is a job for a specialist with the appropriate tools. Having said that, you can still do a workmanlike repair if you take your time and consider the state of the components you're working with realistically. A quick valve stem to guide wear check method. Clean both, then fit the valve into its guide. Withdraw the valve about 1/4" from its seat and try and rock it back and forth. There should be negligible movement. Next, lightly oil the valve stem with engine oil. Refit it to the guide. Place your thumb over the other end of the guide. Quickly withdraw the valve. You should hear a 'pop' sound. This is the sound made by a good stem to guide fit. No 'pop' sound...and it's too loose. There are a myriad of reamers available for the job depending on the type of material being worked and sized. Replacement valves are also available with increased stem sizes to allow for wear and resizing of the guides. That's why k-liners are an effective option when reclaiming worn guides for standard size valve stems. Knurling is another old time process that is still viable...it's effective and low cost, but the guides must still be viable and not totally worn out, as it pulls-up material internally to tighten clearances and provide a surface for lubricant retention. Valve bore gaugeValve bore gauge 2The article below is worth reading. "Sizing Up The Valve Guide" Excerpt: Worn guides will draw oil down the valve stem and will coat or coke on the port side of the valve. This will hinder air flow and cause engine performance to be compromised. Too much oil getting down that valve stem may cause mechanical failure due to the increased possibility of pre-ignition. www.sbintl.com/tech_library/articles/sizing_up_the_valve_guide.pdfThis is the index page. www.sbintl.com/techlibrary.htmlIf it were mine I'd keep the exhaust seats on the wide side to assist heat dissipation. Take your time and don't rush it and it'll work out for you. Don't forget the stem seals!
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Post by Phil Nottingham on Dec 8, 2015 19:00:56 GMT
I would recommend fitting new quality exhaust valves - I always have, as they were well known for loosing their heads
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Post by djm16 on Dec 9, 2015 23:36:47 GMT
Phil, would you like to say from whom you buy your valves, and what you ask for?
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