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Post by paddymk2 on Dec 31, 2016 5:03:37 GMT
Hi All,
I'm putting things back together again and while I can I want to check and adjust the tappet clearance.
I've got the car in neutral, removed the spark plugs and am ready to set the valve-stem to rocker arm clearance.
The manual says clearance of 0.020in -its doesn't mention, but I assume the engine should be cold.
The manual then says to pull on the fan belt to fully open valve 8 (then 6,4,7,1,3,5 &2).
So I've pull on the fan belt (and on the fan for several turns) but I don't see any valves closing.
(Turning things clockwise as facing the fan.)
Am I missing something?
Is there anything else I need to watch out for?
Regards
Paddy
PS Happy New Year and I like the snow!
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Post by dave1800 on Dec 31, 2016 7:01:00 GMT
Hi Paddy
Not sure what manual you are reading but the tappet (rocker) clearance should be set at 15 thou (18 for some early Mk1 engines and 13 for Mk111 engines with the single valve springs and lighter (cam followers) tappets. (All figures for a cold engine and they apply to inlet and exhaust valves)
0.020" (or 0.021" depending on the manual) is the temporary gap when you check the valve timing usually after changing a camshaft or timing chain.
When you turn the engine by hand with the fan belt it is advisable to remove the spark plugs to make it much easier, ensuring no dirt etc can fall inside the bore. You must ensure that the crankshaft turns or the valves will not open and close.
There are several methods but the easiest I find is the rule of 9. When valve 1 is fully open, check and adjust no 8 clearance (1+8 =9), valve 2 fully open check and adjust no 7 (2+7=9) etc. No 1 valve is closest to the radiator. Some like to check the gaps in pairs but if you are unfamiliar then what I suggest should help avoid any confusion.
It is important not to make the gap too small or the valves will not seat and the engine will lose power too loose and the camshaft and valve train wear increases. These engines nearly always sound tappety even when set up properly.
good luck
regards
David
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Post by foglaursen on Dec 31, 2016 9:45:23 GMT
You could also turn the engine the easy way as described by John Twist: Peter  |
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Post by paddymk2 on Dec 31, 2016 12:54:00 GMT
Thanks Guys,
I
I see, you're right (of course) it 0.15in.
Dave when you said, "You must ensure that the crankshaft turns or the valves will not open and close."
Is this just achieved by turning the fan ? Or is there something else to ensuring the crankshaft turns?
By the way the wheels are off and the car is on stands.
It's a Mark 11 Australian automatic model.
Regards,
Paddy
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Post by dave1800 on Jan 1, 2017 0:40:42 GMT
Hi Paddy
What I mean is that if you turn the fan gripping the fan belt you must ensure the crankshaft is turning and the belt isn't just slipping on the crankshaft pulley. If you have the battery connected you can use the method in John Twist's video suggested by Peter (make sure the engine can't start by diconnecting the low tension lead to the coil.
David
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Post by paddymk2 on Jan 1, 2017 8:15:53 GMT
Hi David,
I was not so keen to bump the engine over as per the video and rather wanted to do it the slow & steady manual way - but
Well I'm turning the fan but the valves don't seem to be moving.
Valve 4 is open. I'd expected after a couple of turns to see something move?
Regards
Paddy
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Post by snoopy11 on Jan 1, 2017 12:24:33 GMT
When you turn the fan are you actual tuning the engine when you do it. You may just be slipping on the belt and not turning the engine over. |
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Post by Penguin45 on Jan 1, 2017 13:16:31 GMT
Have you had the head off and the valve gear apart? If so the current clearances may be so large that the rockers aren't moving the valves. Just a thought.
Chris.
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Post by dave1800 on Jan 1, 2017 14:05:50 GMT
Can you confirm
a) the crankshaft pulley IS rotating as you turn the fan pulley holding the fan belt?
if YES go to (c)
if NO
b) rotate the crankshaft pulley using a socket on its securing bolt (it's much easier to turn with spark plugs out)
c) are the push rods moving up and down at all - all of them?
if YES go to (d)
if NO - please let us know what if anything has been dismantled, for example has the timing chain been removed? Was the engine running before any work was carried out?
d) adjust the tappets to 0.015"
regards
David
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Post by paddymk2 on Jan 3, 2017 2:03:42 GMT
Hi David,
Thanks for the logical layout.
So I had my (beautiful) assistant turn the fan and the bottom pulley didn't move.
Conclusion the belt is just slipping - so that makes sense.
I couldn't see how to get a socket on to the crank pulley central nut.
The holder for the fan/radiator assembly is right in the way (with hindsight I could have adjusted this lot when I was changing the water pump.)
When I started the motor last week, there was no fan belt squeal - the tension looks about right: so I'm not keen to over tighten.
I could turning over the engine as per the MGB video but I'm also thinking that if there is no undue tappety tap tap, that I may make things worse. ( I really only thought to check the tappet clearance as I had taken the cover off to paint it.)
If I did try it as per the video, how do you know that the open valve is fully open? (so I can check its counterpart.)
Regards
Paddy
PS Yes this is the first time I'm doing this kind of stuff
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Post by dave1800 on Jan 3, 2017 9:26:22 GMT
Hi Paddy
It should be possible to turn the engine crankshaft by rotating the fan pulley and applying pressure on the fan belt so it presses down hard on the fan pulley. If necessary fully tighten the fan belt temporarily.
You will know when a valve is fully open as it will start closing again if you go too far. Simply keep turning in the same direction (clockwise)until it opens again. There is no need to check them strictly in order or course as long as you keep a note of which you have checked.
Once they are all checked and adjusted you can now repeat the process and see if any valve clearance is too large or tight as you rotate the engine. Sometimes you will find a position where the adjustment is too loose.
As we are not sure how far out of adjustemt your tappets may be it may be wise not to engage the starter.
Good luck!
David
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Post by paddymk2 on Jan 3, 2017 12:51:36 GMT
After skinning my knuckles, I've decided to find a 34mm thin spanner (my bug adjustable is too fat.)
Might be lucky if there's one at work.
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Post by dave1800 on Jan 3, 2017 13:04:23 GMT
That sounds a bit odd it should turn relatively easily. I just realised it is an automatic car. I assume you have it in neutral and not park?
David
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Post by paddymk2 on Jan 5, 2017 8:32:10 GMT
Thanks David,
I did rush down to the garage to check it wasn't in park.
Found it a bit fiddly to tighten the alternator with out my helper.
Luckily my pals at Supercheapoauto had a slim tow ball spanner which did the trick and had it turn.
OK so now im back to it.
Cheers
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Post by dave1800 on Jan 5, 2017 13:46:24 GMT
Glad to hear you found a suitable spanner.
It's a very long time since I briefly owned a crab with an auto box and I can't recall whether it is normal for it to be so difficult to rotate the engine with the plugs out. Certainly on a crab with a clutch it rotates quite easily. Anyone here have any comments please?
David
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