EGR will not hold vacuum

SMILINGDAWG

MEMBER
1979 FORD F-150
5.0L
V8
2WD
MANUAL
200,000 MILES

Vehicle has strong spark knock. Tested EGR with vacuum and tester showed it wouldn't hold vacuum. Bought new EGR from Standard motor products. Tested it with vacuum pump. New EGR would not hold vacuum. Returned EGR and got a replacement. Second new EGR would not hold vacuum. Vacuum tester works good. So two new EGR valves would not hold vacuum or open it's valve. Am I doing something wrong?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

When the vacuum is applied, the pintel should open and the EGR should hold and maintain the vacuum. It doesn't sound like you are doing anything wrong.

If the original one is holding vacuum, does the pintel move when vacuum is applied? If it does, then it's likely good. If that is the case, inspect where it mounts in the intake. See if there is excessive carbon or corrosion that would block air flow.

Take a look at the attachments below. They are the basic diagnostics for the EGR on this vehicle. Hopefully, they will help you.

Let me know what you find.

Joe

See pics below.

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Friday, July 23rd, 2021 AT 10:28 PM

SMILINGDAWG

MEMBER
2 POSTS

I've returned the first new EGR valve, the replacement that I received acts the same way (won't hold vacuum). Since the vehicle is over 40 years old is it possible that EGR valves that have been on the shelf for 40 years could have deteriorated? Is it possible they have a shelf life? These valves were from Standard Motor Products who I thought were a good manufacturer. Having had two new valves fail has got me stumped. The original would not hold vacuum. Do you know of another aftermarket EGR valve manufacturer?

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Saturday, July 24th, 2021 AT 7:58 AM

JACOBANDNICKOLAS