T90 engine(BMC 1.5 diesel) - special spanner 18G 694

[dickh]

Special spanner no 18G 694 for torquing up the cylinder head nuts on the Thornycroft T90 Diesel Engine?
Apparently you need this to do the nuts up in the correct order.
Anyone got one I can borrow or know where I can hire/borrow/buy one?

 

[brianrunyard]

It won't be for doing it in the correct order.
I rebuilt a BMC 1.5 a few years ago, and didn't use a special tool just my trusty torque wrench. I assume it's so the head can be torqued up without removing the rocker shaft.

 

[dickh]

Thats correct - you need it to do the nuts up in the corect order which includes the rocker shaft.

 

[alb40]

The correct order does not include the rocker shaft nuts so the special tool isnt needed unless you want to be lazy and not remove the rockers. Im rebuilding my BMC 1.5 at the moment and havent used any of the 'special' tools

 

[dickh]

Thanks alb40, nice to know I'm not the only one! Have you had any problems with yours? - I'm only rebuilding the top end as one of the heater plugs had been sheared off so I've removed the head.
Where are you getting gasket sets ad other spares from?

 

[alb40]

Im rebuilding the entire engine after one of the combusion chambers shattered and destroyed one piston and the head. Rebuild in in progress and its not running yet. Got a brand new head and new pistons etc to fit into it.
I have done another before that had a sheared glow plug and never had any problems with that one and i never bothered torquing down the head after reasembly and then running.
Getting all gaskets etc from asap supplies and AMC diesel (thornycroft)

 

[owen]

have to partly disagree. the special spanner is needed to comply with the 'book'. it is specified to tighten the nuts underneath the rocker shaft. the rocker shaft has some nuts which are also head nots and so needs to be fitted before the whole is torqued down.
the bad news is that the spanner seems v diff to track down even amc the thorneycroft people do not stock them.
the expert on t90 is reading diesel course who concur that the special spanner is needed.
however i saw my local diesel specialist and he says it would be ok to torque down the head with the rocker shaft absent and then fit the shaft and then torque that down from the centre out.
in the absense of the tool it seems we have no choice

 

[alb40]

The rocker shaft bolts only hold the rocker shaft and are not head bolts as well. They do not go through the head, so the tool is not required unless you want to be lazy and not remove the rocker shaft to torque them down

 

[dickh]

Well. thanks for all the replies, I'll check wether the rocker shaft bolts are also head bolts as I can't remember offhand. I know I certainly removed the rocker shaft and then the head.
Many years ago when I always seemed to be doing head overhauls on mine and friends cars, one always removed the rocker shaft and then the head.

 

[oldharry]

Rebuilt a 1.5 ten or twelve years ago, without the special spanner. Just torqued down everything without the rocker shaft, but following the sequence, then put on the shaft, and torqued down from the centre out, using the same sequence applied to the rocker/head bolts.

Still running perfectly last time I saw it a few years ago, and current owner said it is never been off since, and was running fine.

 

[owen]

Re: T90 engine(BMC 1.5 diesel) - special spanner 18G 694re alb40

just recheched the book. unfortunatley the head bolts do include the rocker shaft bolts . 4 of them are head bolts the others are as u say just bolted to the head and do not go right thro. you cannot take the rocker shaft off without undoing all the head bolts. it seems most people will just torque down the head without the rocker on and then torque down the shaft from middle out.i hope so 'cos i am just about to put the head back on

 

[dickh]

Re: T90 engine(BMC 1.5 diesel) - special spanner 18G 694re alb40

Yes, I agree, I checked the cylinder head last night and will do as you say - fit the head then the rocker shaft torqi=uing from the centre out - unless that is I can source the correct spanner.

 

[brianrunyard]

I've just looked at the manual and agree 4 of the Rocker shaft fixings are also head bolts.
I now remember what that strange spanner is in my tool box. I made it from an old ring spanner, by cutting and welding. The important thing is to keep the two ends on the same axis.

 

[dickh]

Brian, I've sent you a PM