What's the purpose of this vacuum hose routing under this metal plate above water pump?

[fleming442]

Now read my post..I said I cannot pull it out............to see what it is..........come come now.....slow down and read the whole post.

Pffffft. Not with that attitude. Man put there; man can get it out.

 

[pontiacgp]

looks like that is the California set up.....

 

[azmusclecar]

looks like that is the California set up.....

Hmmmmm very interesting.........now I wish I would have checked the teeth on the rear diff gear. The California H/Os
came with 2.56 and every other state got 2.73.
Axle Ratio:

• 2.56 (California emissions)
• 2.73 (49-state emissions)

I will need to try to find another way to verify the build...........the car was sold in Tucson AZ and not in CA but it may be like
you said............a CA built car sold in AZ.

 

[Huen79H/O]

Mine has same vacuum thing behind water pump and I think it was sold new in kc mo and according to the schematic 350 vin R or 403 vin K California. So the 403 is California not the 350

 

[oldsmobile joe]

From my 79 olds service manual

 

[Gwarren79]

Hmmmmm very interesting.........now I wish I would have checked the teeth on the rear diff gear. The California H/Os
came with 2.56 and every other state got 2.73.
Axle Ratio:

• 2.56 (California emissions)
• 2.73 (49-state emissions)

I will need to try to find another way to verify the build...........the car was sold in Tucson AZ and not in CA but it may be like
you said............a CA built car sold in AZ.

You might have a California SPECIFIED car that was sold in AZ. Normal thing. The company or dealership will ship cars to where they are selling.

If yours is a 2.56, I could trade you a 2.73 open

 

[69hurstolds]

Now read my post..I said I cannot pull it out

Better learn how. Otherwise, that's how you get a house full of kids. 🙂

It appears that the metal plate is somehow clipped over the timing cover edge. May be able to pry up on the edge at the cover and move it up and out of the way. That's how it appears from the picture anyway. Not sure if there's any bolts anywhere keeping it where it is. The EGR TCV under there appears it may be a special type of valve.

A note on EGR valves. In my experience, nothing fits better or works as well IMO as genuine GM/Delco emission parts. Now there are companies out there like SMP and Borg Warner, and what not that have made emission parts for GM, but to play it safe with EGR and O2 sensors, nothing has ever shown me to perform and function as intended as the gennie parts. This is based only on my experiences. Yours may differ. And I stay far away from Bosch rebuilt starters/alternators/O2 sensors for G-bodies. Never had any luck with those POS's.

If your car has the original EGR valve, the production number stamped on it would be 17061580 for a CALIFORNIA car. Replacement shelf part number is 17065856 (still shows stamped production number on it). Latest superseded number I've found is 17113418.

Amazingly, if yours is a Cali car and you need a new EGR valve, I found an NOS one for 50 bucks:

http://rover.ebay.com/rover/1/711-5...0001&campid=5335822911&icep_item=183796476965

For the rest of the 49 states, it would show 17056387 stamped on the valve. 17055784 is the shelf part number.

Last cross-reference supersession number where I could find one of these for is 17068202.

http://rover.ebay.com/rover/1/711-5...0001&campid=5335822911&icep_item=352463612061

Interestingly, the final supersession number is ALSO 17113418 which was discontinued in 2012. I guess they gave up and just said all 50 state cars can use one valve. I dunno.

The thing about EGR valves and part numbers- some of them have changed a lot over the years and cross-references make it look like a string board in a detective squad room.

Oh, and check this out. Your vacuum temperature valve (GM calls it a "EGR THERMAL VAC") is part number 560111 (black/yellow). If yours isn't working right......

This valve holds off PORTED vacuum from your carb (above the throttle plates) until the valve reaches a certain temp in the little "oven" it sits in trapping engine heat to improve driveability of the car while the engine comes up in temp. Once the temp is reached, it allows the ported vacuum to go normally to control the EGR valve. It's not 100% absolutely necessary, but without it or if it's failing open when cold, it will operate the EGR when you don't really need it to.

Easy to check. If the valve works, when you start it cold, pull off the hose at the EGR and check for vacuum. There should be none. Blip the throttle by hand. If there's vacuum when cold, the valve failed open. When the engine warms up to some point, it will open and allow vacuum to the EGR. Once the engine is warm, blip the throttle again. If you dont' feel vacuum, the TCV has failed closed and you'll never see EGR. If you feel vacuum, it's doing it's job. Remember, ported vacuum usually has basically NO vacuum signal when at idle.

I found a couple NOS 560111 valves. Here's one for about 40 bucks shipped. Oh, and YELLOW SIDE TO EGR. BLACK SIDE TO PORTED CARB VACUUM. Don't worry, there's labels on the ends to which way it goes.

http://rover.ebay.com/rover/1/711-5...0001&campid=5335822911&icep_item=192873815376

Good luck!

 

[fleming442]

Better learn how. Otherwise, that's how you get a house full of kids. 🙂

 

[DoubleV]

That metal plate should just pop out. If it's not coming out, try harder!

I got one on my 78 non California car. I've seen them on many other Olds of that era. As stated, it's just a cover to hold that thermal vacuum control doo-dad in place.

 

[69hurstolds]

I want to swear I saw one on a T/A with a 403 back in the day, but I'm not holding to it. I had no clue what it was for, and forgot all about it, actually. In those days, it was a smogger, and I held not much interest in said smogger.