Hi,

I recently swapped out my old 305 in my 84 Trans Am for a 350. What is the part in the picture below? It unscrewed from the back of the left head. One of the prongs is broken and I'd like to find a replacement. Any ideas as to what it is and where I can get a new one?

Thanks,
Joe

 

Thats the oil pressure switch for the fuel pump. Once you build up about 5 psi of oil pressure, it sends battery voltage to the fuel pump, in case the fuel pump relay fails.

 

My 84 5.0 h.o had that screwed into the head to. But I dont think it was oil pressure related at all because it threads into basically the accesory bolt holes that you find on the front of the heads if you turn them around. I thought maybe it to be a heat sensor or ground of some sort. But a GMtech knows more but no oil can come out of these holes so who knows what it was for.

 

84's didn't have electric fuel pumps.

My '86 didn't have anything like that on the head. However, it does have a little fan that blows cool air on the carb when the engine is hot, and it has a switch like that in the heater return at the water pump.

 

WTF? got pics of that?

 

Not really. The blower itself is over by the battery inside the fender. Pic shows the hose that goes from the blower to the engine and plastic tube that goes up to the carb.

 

LG4's didn't but L69's should have?

 

Only if dealer installed.

'87 was the only factory installed year.

 

My 84 trans am had the 5.0 ho and it had a electric intake pusher pump & it was definately factory installed

 

Only factory installed year in LG4's.

 

haha, no, no all the LB9s and L98s had mechanical fuel pumps, didnt ya know?

 

The point is an 84 LG4 does not have an electric pump, an 84 L69 does.

 

But, does the originator have an L69 or an LG4? Doesn't say.

Jproz1167, how do you know your pusher was factory and not dealer installed? Did you buy the car new?

 

Still doesn't make sense for a pressure switch to be screwed into the back of the head.

 

Not if it was actually in the back of the head and not just behind the head, no.

Any chance of getting a picture of the end of the threaded part? If there's no port in it I'm going to vote for aftermarket knock sensor or something.

 

five7kid

yes I purchased the car brand new, I recall a recall notice for the 83 h.o and they had the chance to have the electric pump dealer installed due to vapor lock problems

 

i have an 84 TA which i swapped out the 305 for a 350, just finished and am having issues, but, i tried tracking down that little thing myself, what i found out was its a little temp sensor that sits in the back of the head, it just takes the metal temperature, its for a dumby temp light or something. isnt required because i dont have one in and my comp isnt throwing any codes. i'd just leave it out.

 

I completely restored a 1984 TA and I looked into that funny littel switch. It is a temperature probe that has to reach 140 F before it will let the cold air intake in the hood bulge open.........GM found that when the engine was cold, if you hit full throttle, it would open up and let all that cold air in and it would stall. It's written in the 84 GM Service manual..........it took along time to find it!

 

o, wow, that means my cowl is never open atm. i tried to get one of those from the dealer but they were useless. hrm, maybe i should just put my cowl on a switch.

 

I was able to buy a new switch from the local chevy dealer a few years ago......You just need a patient parts guy who will take the time to go look the part up..........the other choice would be to find the connector that went to that switch and just jump it...then the louver will open up any time the system sees a vacuum drop..........ie WOT..... at least now you know what it is!

 

What you are describing is the air injection pump and tubing, it vents air to the air cleaner when not pumping it to the exhaust manifolds or the cat converter.

 

No, it isn't. It's an electric blower to cool the carb, P/N 14094394, mounted over by the battery inside the fender, as recommended in service bulletin 86-34, revised in 87-131. The A.I.R. pump is belt driven and mounted on the engine.

 

I'm not very familiar with F body stuff, I just learned something.

 

I believe this is part number 25036589. Also known in the GM literature as "Switch, Air Int Scoop, DR Thermal". Try that part number with your GM parts guy and I think you will be on the right track.

I highly recommend that you purchase the FBody CD for your Firebird. I have a 1984 as well and I find it very helpful. It is worth much more than the very modest price to purchase it. Looking up parts and part numbers is very easy. Hats off to Mike for making it available.
Brad