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Post by tommydp on Jan 16, 2012 15:06:12 GMT
Hi all! It's been a while and I haven't really done a lot on the car as I've been quite busy with other things.
However, I had some time this weekend. I've now removed the cylinder head and "luckily" found something wrong. All valves/ combustion chambers were dry, soothy black as the car had been idling for ages before I removed the head. One exhaust valve was totally white however. On further inspection it seems there is some carbon on the valve seat and the valve itself, so I suppose it has not closed as it is supposed to. Also, I've taken the cylinder head to others and they agree the valves are way to loose in the guides. I've now got a better cylinder head which I'll try out.
I also had a closer look at the engine mounts and the possible twisting of the engine/ gearbox due to these. I've had some trouble with stiff suspension and a shake at low speed. The whole unit seemed to tilt badly backwards as well as not being level sideways. The big flat mounting had split again and the rear one was not very good either. I'm quite sure this put some force on the driveshafts, playing up the suspension of the car. At least it seemed the car was not suspended at all, felt very stiff when trying to bounce it, on all four wings. I changed the engine mounts for some better ones, and although the big one was slightly split too it improved things. I adjusted the mountings to the chassis to make the engine and driveshafts as level as possible and it improved things.
The car would now bounce nicely when pushing down, on both front wings and the rear ones and I could see the driveshafts flexing on the rubber couplings as I pushed down. Prior to changing the engine mounts the driveshafts appeared stiff in relation to the power unit when trying to bounce the car.
So, looking forward to putting it all together and test the car. Fingers crossed:-)
Really, I'm fed up with these engine mounts. It seems new old stock ones will split too in a few years. Due to age I guess. Have anyone made an improved version? I believe the club offered some once. Anyone know if they still do?
Regards, Tommy:-)
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Post by Penguin45 on Jan 16, 2012 18:31:39 GMT
Hi Tommy,
The Ozzies modified the big flat plate mounting, but I've never seen one.
Chris.
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Post by tommydp on Jan 16, 2012 18:40:49 GMT
Yes, I believe they used two of them. I've never seen it either.
I'm thinking of making my own modified type rather than buying expensive NOS ones which fail within a year or so. I think it would be better to make the engine rest on rubber mountings on the crossmember in some way, alternatively in addition to the original mounting.
Regards, Tommy:-)
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Post by indianajones on Jan 16, 2012 19:08:51 GMT
Hi Tommy, The Ozzies modified the big flat plate mounting, but I've never seen one. Chris. Hmmm I'll have to take some photos of my crab when I get it back as my mechanic reckons I have Aussie mounts. I'll ask him to double check/point it out to me. Also good to see you're working on your crab Tommy, any photos?  -Andrew |
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Post by tommydp on Jan 16, 2012 19:15:26 GMT
Thanks Andrew! I'm afraid I'm a bit slow when it comes to photos.. I'll have to look into it and learn it. I suppose I'll have to use photobucket or something?
Regards, Tommy:-)
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Post by indianajones on Jan 16, 2012 20:04:00 GMT
Try Imageshack ( www.imageshack.us/ ) it's free, pretty simple and no limit if I recall correctly. -Andrew |
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Post by kelsham on Jan 17, 2012 9:15:55 GMT
I heard about the Aussie engine mounting. A friend who was travelling to britain brought one over for me. It comprised of two seperate rubber mountings attached to a cross member.
Sadly when I went to fit it I found the supplied cross member was too short to reach the original body brackets. As I was in a hurry to use the car I retired the replacement to the back of the garage.
Seems the Aussie's also altered the brackets on the body.
Regards Kels.
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Post by dave1800 on Jan 17, 2012 11:49:29 GMT
Hi Tommy, I thought you would be hibernating with the intense cold, but no, you are still working hard; it was only 10C (50F) here last night so I was shivering! I have read that the Landrover Defender engine mount can be fairly easily modified to make a replacement for the vertical large rubber mounting and that the modified mounting is shaped such that it supports the weight in the horizontal plane so there is no shear force trying to rip the rubber from the steel. I haven't seen one, but maybe someone here knows? I found adding the upper tie rod as used only on the 1800S used to help prolong the life of the large mounting quite considerably ; it should be easy to fabricate one. Regards David Hi all! It's been a while and I haven't really done a lot on the car as I've been quite busy with other things. Really, I'm fed up with these engine mounts. It seems new old stock ones will split too in a few years. Due to age I guess. Have anyone made an improved version? I believe the club offered some once. Anyone know if they still do? Regards, Tommy:-) |
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Post by dave1800 on Jan 18, 2012 9:03:06 GMT
Hi Tommy Is the exhaust valve that was totally white in one of the cylinders (3/4) that you noted running weak using the Colourtune? You should try and establish the cause if possible for the valve apparently not closing to see whether you can bottom out the cause. Being white suggests a weak mixture or local overheating - waterway/gasket. As only one valve is white that may rule out too weak a mixture and point towards it getting too hot. It may be an issue within the head and the sloppy valve guides, the valve itself or even a camshaft lobe (sorry!). As I understand it, this head has only been in place since the rebuild not too many kms ago, but I can't recall if you overhauled it in any way or whether the valves and seats have many kms of use and the build up relates to use prior to the rebuild. It would be a shame to put another head on and have the same symptoms,worth more time looking and checking while it's apart IMOH. regards David Regards David However, I had some time this weekend. I've now removed the cylinder head and "luckily" found something wrong. All valves/ combustion chambers were dry, soothy black as the car had been idling for ages before I removed the head. One exhaust valve was totally white however. On further inspection it seems there is some carbon on the valve seat and the valve itself, so I suppose it has not closed as it is supposed to. Also, I've taken the cylinder head to others and they agree the valves are way to loose in the guides. I've now got a better cylinder head which I'll try out. Regards, Tommy:-) |
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Post by tommydp on Jan 18, 2012 20:42:16 GMT
Hi Tommy Is the exhaust valve that was totally white in one of the cylinders (3/4) that you noted running weak using the Colourtune? You should try and establish the cause if possible for the valve apparently not closing to see whether you can bottom out the cause. Being white suggests a weak mixture or local overheating - waterway/gasket. As only one valve is white that may rule out too weak a mixture and point towards it getting too hot. It may be an issue within the head and the sloppy valve guides, the valve itself or even a camshaft lobe (sorry!). As I understand it, this head has only been in place since the rebuild not too many kms ago, but I can't recall if you overhauled it in any way or whether the valves and seats have many kms of use and the build up relates to use prior to the rebuild. It would be a shame to put another head on and have the same symptoms,worth more time looking and checking while it's apart IMOH. regards David [/quote] Thanks Dave! I agree, I should really bottom out the cause before fitting another head. At least now I've got the time to really put it right, as I don't use it in the winter. But honestly, I'm not sure what to look for. It's not even the valve which made the occasional loud tapping sound, which is the inlet on cylinder three. The white exhaust valve is actually the one in cylinder two, ie valve number four. When removing the valve I can clearly see carbon deposits on the valve/ seat, so I suppose this has caused a bad seal when the valve was supposed to be closed. This particular cylinder head has not been overhauled in any way, and has most likely done about 100 000 kilometres.. I only lapped the valves/ seats to a matt grey even surface and changed the oil seals. I cleaned it up very well, so no deposits from prior use. I believe the carbon comes from oil through the sloppy valves/ guides as there's some build up on top of the pistons too. More than you would expect on a rebuilt engine, and the cylinder walls are still fine. You can still se the honing cross pattern marks after the rebuild. As you may recall, I had trouble with another cylinder head earlier. I was uncertain of the so called rebuild of that one, as they had only changed two valve guides etc. IMO the valves seem to loose on that head too. I'm also quite sure cam followers, pushrods and rocker gear are not the problem(s).. Oh, dear, I'm not keen on a cam job again.. Can't believe there's something wrong there to be honest. So, one way I'm keen on trying yet another head, which is by far better when it comes to the "feel" of the valves in the guides, both when valves are closed and open. I can't really think of another way to approach the problem and find a fault and I can fit it in "no time". If it doesn't get better, it's not the end of the world but of course, as you say, the best thing would be to find and confirm what the problem is first! PS! If anyone has information or photos of the use of the Landrover engine mount, instead of the crab's large mount I would be thankful! Regards, Tommy:-) |
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Post by dave1800 on Jan 19, 2012 8:46:23 GMT
I agree it seems most likely that the build up on the valve is probably due to oil because of the wear in the valve guide, but why only on one? Once it starts it quickly gets worse. No2 exhaust valve is adjacent to cylinder 3 exhaust valve so it could be the hottest part of the head, check the waterways between the cylinders and examine the old gasket. As far as the cam goes it maybe worth checking again that the lift and duration of all of the lobes are within spec. Easy to turn the engine by hand with the head off. Your car looks really nice! It's good to see the pics. Regards David I believe the carbon comes from oil through the sloppy valves/ guides as there's some build up on top of the pistons too. Oh, dear, I'm not keen on a cam job again.. Can't believe there's something wrong there to be honest. PS! If anyone has information or photos of the use of the Landrover engine mount, instead of the crab's large mount I would be thankful! Regards, Tommy:-) |
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Post by tommydp on Jan 20, 2012 0:17:44 GMT
Hi Dave, and thank you!
I agree, I should really check lift and duration. Does this mean I have to get into those timing gears again and use a timing disc?
I'm uncertain if I can do these operations accurately enough..
Regarding carbon build up possibly due to valve guides, I've put additional umbrella type oil seals on the valve stems of inlet valves on cylinder one and three, with head in place. Perhaps this can explain the difference between cylinders.
I'll post a picture of the head/ valves tomorrow. Perhaps things get easier now that I know how to upload pics:-)
Regards, Tommy
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Post by dave1800 on Jan 20, 2012 3:18:10 GMT
Hi Tommy I was thinking of a just quick check to see that you are still getting the correct lift; if the lift is OK then this indicates no wear so you can assume the duration is OK too if you, understandably, don't feel like getting your timing disc out. May give you peace of mind and easier while the head is off. Here is a link to an article with photos showing build up on an exhaust valve causing sticking on a Rover engine you may find helpful to compare with your valves? Scroll down the page for exhaust valves. www.robisonservice.com/servicedep/pdfs/carbon_fouling1.pdf regards David Hi Dave, and thank you! I agree, I should really check lift and duration. Does this mean I have to get into those timing gears again and use a timing disc? I'm uncertain if I can do these operations accurately enough.. Regarding carbon build up possibly due to valve guides, I've put additional umbrella type oil seals on the valve stems of inlet valves on cylinder one and three, with head in place. Perhaps this can explain the difference between cylinders. I'll post a picture of the head/ valves tomorrow. Perhaps things get easier now that I know how to upload pics:-) Regards, Tommy |
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Post by tommydp on Jan 24, 2012 0:30:55 GMT
Hi again! It's been quite cold recently, so I have not been able to work on the crab (my garage is inside an old barn..). I've done some investigation on the cylinder head though and I'm quite certain this is the cause of the trouble.
I removed the whitish exhaust valve. The valve seat surface is very rough, and there are traces of carbon there, so I guess it has not closed properly.
The "feel" of the occasionally hammering inlet valve is also suspicious, compared to the others. It appears there is no firm closing fit between the valve and valve seat. Hard to describe, but I try: I removed the valve springs. As I keep the valve in the closed position by hand I try to move it sideways by the upper part of the valve stem. The valve head then moves off the seat, opening the valve slightly. So it seems the valve and seat do not make a firm seal in the closed position. This does not happen on the other inlet valves.
A you may recall, this very valve made an irregular loud tapping noise while the other valves were reasonably quiet. The vacuum gauge fell from 20 to 18 as this sound occured, and the engine missed in relation to the sound.
Before I put another head on, I would like to check the valve lift. The most accurate way I can do it, is measuring pushrod movement from lowest position to peak position of the cam lobe. Will this do? At least it would give some indication, I hope. I'll measure all eight.
Well, updates to come:-) I'll heat up the garage and do some work one of the following evenings.-) I don't really mind low temperatures at all, but working on mechanics below - 10 Celsius is awkward, your breath turns to frost on steel etc and I don't want to expose the open engine block to that. I've cleaned the piston tops and oiled the cylinders lightly. I've then wrapped old newspapers and cardboard around it, covered by blankets and a reindeer fur on top (!) so it will be OK.
Best regards from the frozen north.-)
Tommy.
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Post by Penguin45 on Jan 24, 2012 1:01:10 GMT
If it is just the one worn valve guide, Tommy, and the head is otherwise fine, why not replace it? A guide is cheap enough, changing the valve itself will not be expensive, then it is just a case of lapping it in to restore the sealing surface. New parts will give you confidence that the job is "right".
Chris.
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