Rebuilding my type 4, Haynes tells me the relief valve spring should be 39mm long under a pressure of 17lbs +/- 2lbs. That's over 7.7kg! Any tips for balancing a mass that large on a spring that's about 15mm diameter in such a way that I can accurately measure the length? Is it safe to assume that if both valve and spring look ok, no scratches or burrs, slides nicely, that I just put it back in?
Having said that there are very light wear marks on the valve. I've held so the light shows it, but it's very light wear. Anything to fret about or just pop it back in?
A £2 coin was a lovely snug fit for the plug slot and I was going to recommend it held in a pair of adjustable grips... until I just popped the middle out of the coin! Built-in protection from over torquing. Oops!
If it’s a later type 4 case it only has one pressure relief valve next to the oil filter. If its an early case the other valve is between the cam follower bores.
Use a block of wood (or metal) 39m thick and drill a hole large enough for the spring to drop in. Place the block with the spring on your scales and set to zero, push the spring until it’s just flush with the block – the pressure should be 6.8kg to 8.8kg. Free length of a new spring is 63mm and should give the correct loaded pressure. Don’t be tempted to use a shiny high-pressure spring.
Don’t know if it’s the correct way to measure the spring but I did it by pressing down on the spring on some bathroom scales to 7.5 kg or so while measuring the length. Seems fairly accurate. That relief valve does have some wear however it is probably a better fit & less likely to jam in the bore than an aftermarket one.
It would have had hydraulic cam followers but you’ve probably got rid of them and fitted a solid cam and followers.
Yep single relief case the same as the one i have rebuilt for my bus. Only down side i have found compared with the dual relief case is high oil pressure when cold. Seems to be the norm though.
Talking of which, I thought it was going to be an easy job to fit a new cam. Reading Deefer's engine rebuild thread it seems I'm going to have to drill out the rivets to use the gear. Oh well
It’s worn but probably serviceable – check the bore very carefully and make sure the valve slides in and out without jamming.
Smooth as a smooth thing. As I tried to remove it the resulting vacuum was enough to draw it back in. I shouldn't have any wear issues I think
I’d use a new aluminium gear and it’s not just drilling out the rivets – you must check the cam bolt clearance to the oil pump. Which cam are you going to fit?
You will need to drill out the rivets and get it machined for clearance to the oil pump. Or do what i did & fit a new bolt on gear
