steering pump leak?
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 825
Likes: 40
From: Glasgow, Scotland
steering pump leak?
I fitted the hydroboost kit a few months ago, the steering pump starting leaking a short time after fitting the hydroboost, so I thought I would get a new pump, fitted it on, but still have a leak, seems to be coming from the main steering pump outlet, one of the hydroboost pipes goes into it, it takes quite alot of tighting of the pipe to get it to tighten up, cant get it any tighter, but it still leaks a small amount, I was thinking does there need to be a rubber o ring inside that fitting, or is it ment to be metal to metal??(i have a 78 corvette with a pump ment for that year)
cheers
dave
cheers
dave
Le Mans Master
Joined: Jul 2000
Posts: 6,001
Likes: 112
From: Saginaw Michigan
Through the 1979 model year all GM power steering pumps and gears used 45 degree flare fitting connections with either 5/8-18 UNF or 11/16-18 UNS threads. Starting in 1980 all GM power steering pumps and gears were converted to metric o-ring type connections. The ports and nuts were M16X1.5 or M18X1.5 threads.
Your 1978 pump should have a 45 degree 5/8-16 discharge port. However, be aware that a 1980+ metric pump discharge fitting will interchange into older GM pumps.
Here is a picture of the two ports. The 45 degree flare connection with a 5/8-16 UNF thread (1st design) is not real clear. The M16X1.5 metric o-ring port (2nd design) is better detailed.
Normally, if you have a leaking fitting you have a couple possibilities. Power steering hose assembly pipes are made from welded tubing. Sometimes a forming crack could occur right at the weld seam. The crack could be quite small but a leaker.
5/8-18 threads are very close to M16X1.5 threads. In other words a 5/8-18 UNF male nut will thread into a metric M16X1.5 port. And vice versa: A M16X1.5 male nut will thread into a 5/8-18 port. However, the 45 degree formed tubing end and the metric o-ring formed tubing ends will not seal in the other type ports.
Jim
Your 1978 pump should have a 45 degree 5/8-16 discharge port. However, be aware that a 1980+ metric pump discharge fitting will interchange into older GM pumps.
Here is a picture of the two ports. The 45 degree flare connection with a 5/8-16 UNF thread (1st design) is not real clear. The M16X1.5 metric o-ring port (2nd design) is better detailed.
Normally, if you have a leaking fitting you have a couple possibilities. Power steering hose assembly pipes are made from welded tubing. Sometimes a forming crack could occur right at the weld seam. The crack could be quite small but a leaker.
5/8-18 threads are very close to M16X1.5 threads. In other words a 5/8-18 UNF male nut will thread into a metric M16X1.5 port. And vice versa: A M16X1.5 male nut will thread into a 5/8-18 port. However, the 45 degree formed tubing end and the metric o-ring formed tubing ends will not seal in the other type ports.
Jim
Last edited by Jim Shea; Jul 5, 2009 at 10:42 PM.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 825
Likes: 40
From: Glasgow, Scotland
Through the 1979 model year all GM power steering pumps and gears used 45 degree flare fitting connections with either 5/8-18 UNF or 11/16-18 UNS threads. Starting in 1980 all GM power steering pumps and gears were converted to metric o-ring type connections. The ports and nuts were M16X1.5 or M18X1.5 threads.
Your 1978 pump should have a 45 degree 5/8-16 discharge port. However, be aware that a 1980+ metric pump discharge fitting will interchange into older GM pumps.
Here is a picture of the two ports. The 45 degree flare connection with a 5/8-16 UNF thread (1st design) is not real clear. The M16X1.5 metric o-ring port (2nd design) is better detailed.
Normally, if you have a leaking fitting you have a couple possibilities. Power steering hose assembly pipes are made from welded tubing. Sometimes a forming crack could occur right at the weld seam. The crack could be quite small but a leaker.
5/8-18 threads are very close to M16X1.5 threads. In other words a 5/8-18 UNF male nut will thread into a metric M16X1.5 port. And vice versa: A M16X1.5 male nut will thread into a 5/8-18 port. However, the 45 degree formed tubing end and the metric o-ring formed tubing ends will not seal in the other type ports.
Jim
Your 1978 pump should have a 45 degree 5/8-16 discharge port. However, be aware that a 1980+ metric pump discharge fitting will interchange into older GM pumps.
Here is a picture of the two ports. The 45 degree flare connection with a 5/8-16 UNF thread (1st design) is not real clear. The M16X1.5 metric o-ring port (2nd design) is better detailed.
Normally, if you have a leaking fitting you have a couple possibilities. Power steering hose assembly pipes are made from welded tubing. Sometimes a forming crack could occur right at the weld seam. The crack could be quite small but a leaker.
5/8-18 threads are very close to M16X1.5 threads. In other words a 5/8-18 UNF male nut will thread into a metric M16X1.5 port. And vice versa: A M16X1.5 male nut will thread into a 5/8-18 port. However, the 45 degree formed tubing end and the metric o-ring formed tubing ends will not seal in the other type ports.
Jim
thanks alot for that info
dave
