Vacuum Pump
 

1985 300TDT - Took vac reading from one of the connections off vac hose (from vac pump to brake booster) at idle - reading was 20 in. From what Ive read - is this normal? Car has about 125K miles. I've read about (in this forum) oil in the air cleaner getting in there by way of a "tear" in the vac pump diaphragm. If a tear happens - there should be A LOT of oil in the air filter, and vacuum reading would be lower than 20 in?? Thanks.

I was out driving when mine tore... and it was immediately manual brakes ... a lot more pressure to stop the car... no mistakeing it... and it would not shut off by the key also...
The amount of oil was significant visually but not gushing... I drove the car , to get home , about 20 miles.... if that is any help... on my car the oil was inside the aircleaner because of the position of the tube from the pump.... but I don't think all are that way..
I think your diaphram is ok from what you have described....

I thought diaphram pumps ended sometime in early 1981 and the latter cars all had piston style pumps???

Sounds reasonable, but to compare with spec you need to measure differently. Take the fitting off at booster. Plug it with your finger, then take the measurement with only the gauge.



Michael

Now I know how easily old plastic can break - one of the feeds from the main vacuum hose (from vac pump) broke off as I was changing rubber 4-way connection. Just received part today - glad it was'nt too costly! Will need to be a little more gentle with these things!

Leathermang and samiam - thanks for the info! Hey that vac line from pump to brake booster ($) not too bad - about $26.