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Anon Deleted Posts : Location : Status : Offline |
Next Task - Camshaft housing gaskets Any advice / input welcomed to build my confidence in the next (and possibly largest to date) job on the to do list... assuming we make it to shropshire & back ok over the easter weekend.We clearly have some very leaky gaskets on our engine, dripping onto the exhaust manifold & smoking during warm up and also onto the (nice, new, shiny) alternator. And on the other side pooling on the top of the crankcase. Prime suspects are clearly the camshaft cover & camshaft housing gaskets. Having read Phil's breakdown here: Howto, cylinder head I have a bit more confidence I can work through this with only occasional crisis of confidence! I'm kind of hoping that the cylinder head gasket isn't also a source of leaks, and assuming I'd have bigger problems evident if that was the case ? Should I just bite the bullet & go for replacing all three ? (does the cylinder head need coolant draining & renewing too..?) Assume I should be checking tappet clearances at the same time also ? I have a new timing belt to go on as I've no record of when it was previously replaced and already noted that the fan belt needs replacing. Oil filter is long overdue for renewal so will likely be doing this & changing the oil around the same time. Any other jobs worth doing at the same time ? Both excited and a little anxious at taking getting my hands dirty to the next level..... although mrs_m will be very happy to have a clean engine to polish instead of the current gunky lump. |
 Tue 27 Mar 2012 @ 10:36
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Anon Deleted Posts : Location : Status : Offline |
Cylinder head gasket normally doesn't let oil leak through but the O-ring seal for the camshaft oil feed can. Check for seepage running down the side of the crankcase just behind the distributor/oil pump. Leaks running towards the back of the engine usually are from the cam cover and, or, camshaft housing gaskets. Camshaft cover leaks can be sorted without needing to mess with the cambelt & until the cover is sorted it will be hard to figure out if there are any leaks from under the camshaft housing. Do the camshaft cover leaks as part of valve clearance adjustment. I.e., warm up the engine to normal operating temperature, whizz off the cover & adjust the clearances while the engine is hot after which the engine can be let to cool down before putting it back together. At the same time you'll know from adjusting the valve clearances whether you'll need under-size adjuster screws (or more ...) & can plan accordingly if the head is likely to come off. So, to save head scratching & back-tracking, do a cylinder compression check before removing camshaft cover & adjusting valve clearances. PS Link to the Howto wouldn't work so I've edited it. 
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Tue 27 Mar 2012 @ 12:17
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Anon Deleted Posts : Location : Status : Offline |
Thanks Phil (as ever!) I'll acquire a compression tester and get that done... can also check out the state of the plugs.. actually i have a spare set i had planned on replacing with as again the current ones are of unknown heritage! If I replace the camshaft cover gasket.... and then have to work down to the camshaft housing gasket... will i have to replace both (i.e. end up replacing the cover gasket twice...) ? |
Wed 28 Mar 2012 @ 09:29
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Anon Deleted Posts : Location : Status : Offline |
ed_m wrote: If I replace the camshaft cover gasket.... and then have to work down to the camshaft housing gasket... will i have to replace both (i.e. end up replacing the cover gasket twice...) ? Yes, but if the leaks stop once the cam cover gasket is replaced then the housing won't have to be disturbed. Compression test then adjusting valve clearances might be the decider, like finding something to mend that involves lifting the camshaft housing. ---------------------- |
Wed 28 Mar 2012 @ 09:54
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Anon Deleted Posts : Location : Status : Offline |
Fair enough.... new cover gasket on order ( I think it may be a thick one too ).
Will plan for compression test & plug change.... give engine a good clean & replace gasket. (Goodness knows when mind!) |
Wed 28 Mar 2012 @ 15:59
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Anon Deleted Posts : Location : Status : Offline |
ed_m wrote: new cover gasket on order ( I think it may be a thick one too Genuine Payen JM550 is the thick one that's comparable to original GM. ---------------------- |
Wed 28 Mar 2012 @ 17:32
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Anon Deleted Posts : Location : Status : Offline |
ok its official... i hate the thing ! 
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Tue 05 Jun 2012 @ 13:50
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Anon Deleted Posts : Location : Status : Offline |
philbradshaw wrote:
Compression test then adjusting valve clearances might be the decider, like finding something to mend that involves lifting the camshaft housing. Is there a suitable how to for valve clearances ? Have seen the LPG conversion one which is all nice and cleanly on the workbench! 
I guess I'm missing the bit on how best to get at / turn the shaft to check each clearance in turn... Assume the clearances in the LPG thread still stand. Tah. |
Sat 14 Jul 2012 @ 20:31
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Anon Deleted Posts : Location : Status : Offline |
In situ valve clearance check is in Vauxhall OHC cylinder head removal and installation (near the end): turn engine via crankshaft pulley bolt (3/4 inch AF head). ---------------------- |
Sat 14 Jul 2012 @ 20:55
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Anon Deleted Posts : Location : Status : Offline |
Tah, what size hex are the adjusters? My feelers seem to be metric sorry, only checked no4 exhaust so far which comes out at 0.019" rather than 0.015". Adjusters look to be a few turns below the start of the thread on exhaust and a little proud on the intake. |
Sun 15 Jul 2012 @ 14:59
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Anon Deleted Posts : Location : Status : Offline |
Adjuster screws hexagon is 1/8 inch. Metric dimensions are in tech data at the end of the OHC cylinder head removal and installation HowTo (i.e. the link in my previous post). Allow about 0.003 inch per full turn of adjuster screws: 0.019 inch plus a turn should come out about 0.016 inch. Standard adjuster screws wound out so far that they're only a thread or two from protruding from their tappets when valve clearance is correct usually indicates valve seat recession. Standard adjuster screws wound in similarly usually indicates valve stem tips ground to accommodate either seat recession or valve seats installed but not finished to optimum valve stem height. However, first or second under-size screw can have the same effect so check the blind ends - 
Standard screw (1) has a flat inner (blind) end. First undersize screw has a tapered inner end and the tapered flat extends to the outer end of the screw. Second undersize screw also has a tapered inner end but the tapered flat only extends to within four threads of the outer end of the screw. ---------------------- |
Sun 15 Jul 2012 @ 16:17
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Anon Deleted Posts : Location : Status : Offline |
hmmmm tah... so worth taking one or all of the screws out to have a look at while i'm there ? i wouldn't say either are at the extremes but i can see a few threads in either direction when peering into the tappets with my torch. (assuming i don't drop them into the depths) |
Mon 16 Jul 2012 @ 07:30
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Anon Deleted Posts : Location : Status : Offline |
Camshaft housing should be removed in order to remove tappet screws. If the valve springs are a bit tired then you might get away with not removing the housing first but it's not something that I'd recommend. ---------------------- |
Mon 16 Jul 2012 @ 11:06
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Anon Deleted Posts : Location : Status : Offline |
Went armed with a 1/8 allen key this evening and did an initial reading on all the valves... at 0.003inch/turn all need between 1 & 2 turns to get to the minimum value (which i assume is the target? as the range is quoted hot, which it's not). Only one needs 2 turns, but i need to recheck the measurement. I bottled out trying to turn the adjusters when i was putting a fair bit of force on the short end of the allen key, but in hindsight i guess it needs enough force to overcome the valve spring. May need to fashion a better handle for the allen key or find a better tool (as per phil's photos). All good learning experience mind. |
Thu 19 Jul 2012 @ 19:57
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Anon Deleted Posts : Location : Status : Offline |
Ok managed to do it with the allen key, ok once you get a feel for it
Using 0.003inch per turn as a guide i gave them all a turn clockwise apart from number 1 exhaust which was just about in range already. (plus it was the last one i did and having seen how the others changed). Here's a nice little table: 
Pretty certain i only made one turn, the click back onto the flat is pretty obvious, but that'd make it more like 0.006 inch/turn. So now most are under the minumum value, and a turn back again in theory puts them over the max (doh). Not sure how much error i expect on my measurement with the feeler gauges either. Which option would be best ? ! too tight or too loose ? 
(thanks) |
Fri 20 Jul 2012 @ 18:51
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Anon Deleted Posts : Location : Status : Offline |
Really need the engine at normal operating temperature to set the valve clearances ... Using 0.007 and 0.015 inch for intake and exhaust respectively, adjust until feeler blade/s nipped and won't pull out then back off one turn. Once each adjustment is made, make sure that 0.010 inch (intake) and 0.018 inch (exhaust) feeler blades can't be inserted. There's no need to be fussy about what the final clearance is as long as it's above minimum spec. You may find it simpler to do all intake then all exhaust - less messing with feeler blades. Once the engine is warmed up it's worth checking the clearances again, more for the one or two that go tight than the ones that go slack and start tapping. ---------------------- |
Fri 20 Jul 2012 @ 19:24
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Anon Deleted Posts : Location : Status : Offline |
yikes... so.... ummmmm 
no chance i'd have had the confidence/time to get the thing warmed up... then do the compression check.... then whip the cover off and do clearances whilst still hot ! So guess I should back them off again, sort out the new gasket and nip the cover back on to get the thing warmed up. On which note here's the cover on which the nuts/bolts were barely over finger tight:  
And an attempt to view down the mating surface.... looks fairly true, maybe some indentation around the nut / bolt points (right hand side still had remains of old gasket): 
Do these need truing up before proceeding?... careful clamping in a vice sufficient ? And finally... one of the studs came off with the nut on the inlet side, assume this can just be screwed straight back in ? Sorry for all the q's .. this is really quite a long way out of my comfort zone 
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Fri 20 Jul 2012 @ 20:48
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Anon Deleted Posts : Location : Status : Offline |
Do the valve clearances first. Leave the coil bracket detached but supported so that the engine can be run. Also leave off the air cleaner but block up the two small bore vacuum hoses (one to carburettor, one to intake manifold). Operate choke and throttle by hand to start and warm up engine. Longer working time can be had by warming up the engine until the bottom radiator hose feels hot to the touch but there's a good 30 minutes to play with anyway so there's no rush needed. Once valve clearances are done, put everything back together less coil bracket and air cleaner and warm up the engine again in order to do the cylinder compression check. Once that's done and any leaks or niggles are sorted the coil bracket and air cleaner can be fitted. Cam cover looks good but the distortion around the fixing holes is best flattened out (pin hammer + socket or similar as a mandrel on the top side of the cover). The loose stud is best installed before the cam cover. Once the nut is removed and the stud threads are clean, lock two nuts together on the fine threads end of the stud. Apply thread locking fluid, e.g. Loctite blue, to other end of stud then install stud hand tight. Allow 5-10 minutes for the glue to cure enough to withstand the nuts being slackened and removed. If the cam cover gasket is about 5mm thick (GM original or Payen JM550) then it should survive the cover being lifted once the engine is warmed up. If the gasket you have is much thinner then go buy another one just in case it doesn't survive. ---------------------- |
Fri 20 Jul 2012 @ 22:22
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