Rocker Cover torque

[agroman]

Hi all
Been a while since last post - Dexta generally working well following rebuild, however do have a few oil leaks to sort. Worst one is the rocker cover. I have had a couple of failed attempts on something that should be straight forward! I have found that the Agriline gasket is a better fit than a Vapormatic one - which appeared completely the wrong size. I used some high temp copper silicone which worked for a while, so I have gone back to Hylomar Blue to stick the gasket to the cover and a bead on the head surface.
Does anyone know the correct tightening torque for the 2 rocker cover nuts?
I can't find it in the workshop manual.
If you tighten too much it squeezes the gasket out at the front of the engine just behind the thermostat housing. There is no lip on the rocker cover along this front edge. I assume this is how it is supposed to be as it look as if the cover hasn't been hacked about!

[Bensdexta]

The front of my rocker cover looks like below.
Not sure why the lip on the flange is missing at the front but assume it's original, and not been butchered. Perhaps it's to allow any excess gasket to bulge out at the front? Does anyone know why it's cut away like this?
(BTW Photobucket seems most unwieldy these days, and doesn't seem to display the size of photo that I want (width 640pix), or maybe it's FTP that's misbehavin' ?! )

[agroman]

Thanks Ben
That's exactly the same as mine. Also not sure why the long part of the flange is missing. The small bit on the angle is due to the position of one of the head bolts. Think I have sealed mine up now. New gasket and hylomar also let it go off for an hour or so with the gasket in position on the cover then fit to head with a smear of Hylomar all around and tighten until you think you are about to squeeze the gasket out at the front where the flange is missing. Check carefully that the gasket is still in the correct place all around especially the corners. Then let go off over night before starting. Also found that I had oil being blown up around the head studs that hold the injectors in place. So I would recommend tightening the head bolts once or even twice when hot and its been run for a while. Need to make sure you have some spare injector washers as you will have to take them out to tighten the head bolts. Ideally you will need a deep 11/16 socket to fit over these longer studs. I used a 17mm which was a little small and needed a bit of force to get on nuts, but that is all I had! Also rocker gear needs (+ oil supply pipe) to come off to tighten the other head nuts. Tighten bolts to 60 lbs/ft

[Bensdexta]

... Also found that I had oil being blown up around the head studs that hold the injectors in place. So I would recommend tightening the head bolts once or even twice when hot and its been run for a while. Need to make sure you have some spare injector washers as you will have to take them out to tighten the head bolts. Ideally you will need a deep 11/16 socket to fit over these longer studs. I used a 17mm which was a little small and needed a bit of force to get on nuts, but that is all I had! Also rocker gear needs (+ oil supply pipe) to come off to tighten the other head nuts. Tighten bolts to 60 lbs/ft

Thanks for the helpful info. Where can one get a 11/16" deep socket - needs to be pretty deep ?

I believe you can get an open-ended spanner with a socket at the end for a torque wrench, which would avoid removing the injectors. Then just reduce the torque setting to account for the extra length of the open-ender. Would this do the job?
http://www.ebay.co.uk/itm/Britool-11-16 ... 3641.l6368
or flare nut crowfoot:
http://www.ebay.co.uk/itm/like/14175696 ... ue&ff13=80

Meanwhile I've ordered a long open-ended 11/16" spanner and will do up the injector studs 'tight' by hand.

[Brian]

If you Google Britool Sockets you get loads of suppliers of top quality sockets including deep ones. I have been using Britool sockets for 50 years and still have most of my original set, still under warranty if I break one! I got my 11/16th deep one about 2 years ago.

[Bensdexta]

If you Google Britool Sockets you get loads of suppliers of top quality sockets including deep ones. I have been using Britool sockets for 50 years and still have most of my original set, still under warranty if I break one! I got my 11/16th deep one about 2 years ago.

Brian, thanks for the tip.

Is a 'bi-hex' spanner the same as '12-point' spanner?

Perhaps a flare crowfoot would be good enough, and save having to remove the injectors, and maybe the rockers also?

[Timeee]

Going back to the the rocker cover gasket moving, I can suggest a good solution that we used for years on BMC A and B series engine rocker covers that suffered from the same problem (and of course Dextas). I use it on all engines that have a relatively thick cork-type gasket that tends to slip out as you tighten them down. Just use ordinary spray adhesive (same stuff we used to stick car carpets and vinyl upholstery). Clean the rocker cover gasket area with brake cleaner, then spray the adhesive on both surfaces to be stuck together (the rocker cover gasket face and the gasket). Wait a minute to let it go tacky and then press the gasket to the rocker cover. Once stuck in position on the rocker cover,you can use blue hylomar, or wellseal for the gasket to cylinder head seal, before fitting to the cylinder head.
The usual source of oil leaks was people tightening the cork gasket too tight, rather than just "nipping" it. Hope this is of help to someone.

Tim E

[agroman]

Interesting idea which must work. I am surprised that the 'carpet' glue can stick the heat and the oil for any length of time? Mine with Hylomar both sides of the gasket appears ok so far. It's clocked up several hours over the last week or 2.

[Bensdexta]

....So I would recommend tightening the head bolts once or even twice when hot and its been run for a while. Need to make sure you have some spare injector washers as you will have to take them out to tighten the head bolts....

Any reason why I shouldn't re-use my old copper washers, after first annealing them by heating to cherry red?

[Bensdexta]

I believe you can get an open-ended spanner with a socket at the end for a torque wrench, which would avoid removing the injectors. Then just reduce the torque setting to account for the extra length of the open-ender. Would this do the job?
http://www.ebay.co.uk/itm/Britool-11-16 ... 3641.l6368
or flare nut crowfoot:
http://www.ebay.co.uk/itm/like/14175696 ... ue&ff13=80

Meanwhile I've ordered a long open-ended 11/16" spanner and will do up the injector studs 'tight' by hand.

Note: Sadly my 11/16" crowfoot won't get on two of the head bolts, so removal of the rocker is still needed. Neither will it get on the nuts under the injectors.

Also undoing the union nut for the rocker oil feed, at the rear right of the head is awkward. My 7/16" crowfoot is perfect for this.

I'm relieved to rediscover that the engine can be turned over by levering a screwdriver on the flywheel through the SPILL/TDC window on the front LH side of the clutch casting - so no problem there.

[Bensdexta]

Re-torqued my head nuts yesterday.

None of them moved - trust they weren't over-torqued in the first place, or may be the friction has inceased?

It's quite a scramble to get everything apart before the engine cools down!

A useful link on tappet adjustment here:
http://www.agriline.co.za/technical/set_tappets.html

I had forgotten how fiddly adjusting tappets is - you need three hands.

[Bensdexta]

Put my rocker cover back on today.

But the new cork gasket (Sparex) was too big, so I cut it through at the front, 'shortened' it by carefully cutting out about 1/8" and glued the ends back together with Evostick. Then Evostuck the whole gasket to the underside of the rocker cover. Refitted and hey presto - no oil leak!

No need (yet) for the Hylomar mentioned on the link ^ between head and gasket.