brakes

[preec]

When I press brake pedal first time =ok. when press again shortly after it can go "wooden"and harder to stop than normal. after a short time things fine again.(vacuum)?.

What could be problem

How easy to fix

possible cost.

After my auto box rebuild etc I would of course like a positive answer but am prepared for the worst.

 

[Raistlin]

Is it a diesel Colin?

 

If so, it's a gradual vacuum loss on either brake servo or vacuum pump. Both of which are ridiculously expensive new but thankfully easily obtained second hand on fleabay.

The servo will have a part number label which is visible if you lift the felt cover just under the passenger side windscreen in the engine bay. You MUST get the right part number or else it will not fit, even though it might initially look OK (Been there - got the T-Shirt).

Most likely to be the servo as they are prone to contamination degrading the seals.

The vacuum pump should, IIRC, produce 18 inches of mercury vacuum when working properly.

If it's a petrol then it is certainly the servo unless there is a small vacuum leak in a pipe.

 

Hope that helps?

[preec]

having thought a bit more.Would culprit most likely  be vacuum pump ?  expensive?.

Vacuum piping looks ok 

[Old_Growler]

15 hours ago, preec said:

When I press brake pedal first time =ok. when press again shortly after it can go "wooden"and harder to stop than normal. after a short time things fine again.(vacuum)?.

What could be problem

How easy to fix

possible cost.

After my auto box rebuild etc I would of course like a positive answer but am prepared for the worst.

 

From your description it does sound like the brake booster as they get corrosion inside and this might have shifted while the auto box was serviced. 1st I would check the plastic pipe with the check valve as if the engine been left to hang it may have pulled on the grommets and leak. Run some watered down washing up liquid around the grommets while getting someone to rev the engine. OME parts on old cars are a no no..A pattern part brake booster will cost between £120-170 and take about 2 hours to replace.

These technical service bulletins may be of help to S type owners: www.jagrepair.com/s-TypeTSB.htm