308qv Air Pump (CAM) Pulley

I had the same problem with my '83 QV. If you're leaking oil (mine did), it would not be from the spindle becoming merely "disconnected" from the cam drive. The "shear" pin and shaft you're referring to are the same part.

The first thing I would check is to see if the spindle has not sheared. This would cause the pulley not to turn. Secondly, there are two straight pins that connect the spindle to 1) the cam 2) the pulley. The inner straight pin fell out on mine. In the process of slipping out, one of the pins, while rotating, bore a hole into the endplate (cam cover) which caused an oil leak. Below is a picture of the endplate:

http://cgi.ebay.com/ebaymotors/Ferrari-308-QV-Cover-/120560987450?pt=Motors_Car_Truck_Parts_Accessories&hash=item1c11fead3a

If the problem is just the pin slipping out, you might try some loctite (can't remember the Loctite product no.) to secure it in place. This didn't work on mine. I ended up using a zip tie to secure the pin in place (tacky, but it works).

Lastly, if the spindle did shear, check to make sure the air pump didn't freeze up. Just replaced my frozen air pump with a new one.

 

Glad to see that the leak went away. The zip tie works well. The one I used is about 1/4" wide and was able to get it on (barely) with the pulley in place. The hub of the zip tie should fit neatly into the recess on the back side of the pulley. I used Loctite 609 on the front pin and it worked well but ended up using a small hose clamp on the outer pin. Funky but easy off and easy on. Wonder where the oil leak was coming from?

 

4valve,

I also bought a box of 4mm(?) pins from MacMaster-Carr and as you said a tad small. I even bought one from Ferrari with the same problem, a tad small. Guess you'd have to machine an exact oversized one that can be pressed fit. BTW, I ended up using a spring pin from a local Orchard Supply Hardware (e.g. http://www.mcmaster.com/#pins/=e4ro6n) which works well too cause the solid pins just slip through.

 

I am going through all of this on my qv right now. The air pump drive on the end of the cam just spins on the end of the cam, it doesn't turn the pump. And I have an oil leak right here as well. If I put this pin in my oil leak might stop? That would be excellent! Does anyone have the TAV that shows these parts and assembly? I need to get my car to pass California smog.

I am concerned that 4valve used an OSH roll pin in here. If this is truly supposed to be a shear pin in this location then the purpose of that pin is to break and stop driving the air pump if the air pump fails and jams. If the pin doesn't shear then something else will give way. If it is the teeth on the timing belt that break then you are at the beginning of a very bad and expensive day.

I took the pump apart, lubed everything, spun it with a drill for a bit to make sure everything was smooth. I just need to get a pin to drive the pulley.

 

I have a TAV of the air pump assembly but I'm out of town till the middle of week. Can send a jpeg of it this coming Wednesday or Thursday. PM your email address if interested. More likely what has happened is the the coupler spindle has snapped (see my prior posting on this thread from 9-18-2011). To see if this is the case, you would have to remove the air pump pulley. I still don't understand where one could get an oil leak here pin or no pin, sheared or not.

The roll pin is just to keep the coupler spindle connected to the cam shaft and/or air pump pulley. The safety valve (or shear) takes place on the coupler itself where a portion of this 2" rod is narrower at its "waist" and if the air pump freezes, it will shear at this "waist." It has nothing to do with the retaining pin or roll pin.

 

Ahhh! I finally remember why oil leaks if the retaining pin(s) falls out. I had forgotten that there is an o-ring (part no. 49 or 118018) on the coupler that provides an oil seal. If the pin comes out, the coupler comes out and it leaks. Hopefully, yours can pushed back in. I'd replaced the o-ring if you've gone this far. 4valve and I both had some difficulty finding a pin that would hold securely...thus the use of a zip tie to keep the pin in place. I used a roll pin instead of a solid pin because it actually provided a tighter fit. Good luck.

 

I'm resurrecting this thread because well, it just happened to me. The first time it happened the pin didn't come all the way out and began making a chattering sound as it started on it's task of chewing up the end plate. But it was still there so I applied some Loctite and pounded it back in. That worked for a month or so but I kept watching it and sure enough it began sneaking it's way out again so more Loctite and I tried staking the end with a punch but alas, this time it got away on the first run. I was at my hangar and didn't want to chance the drive home since there is nothing holding the pulley and it's shaft in but the o-ring and if it comers out it would be a big mess. So I cut the end off of a punch that was a near fit although a bit loose then wrapped safety wire around the end of the cam over the pin so it couldn't get out.

The pin I'm talking about is #54 p/n 100279 in the parts diagram and is listed as a spiral spring pin so all I need to do is figure out what size. FWIW, what was in there was not a roll pin, it was a solid taper pin.

Also, having had this whole thing apart when I did my heads I can clear up the whole "shear pin" theory. That is not a shear pin. The safety shear for the pump pulley is that barbell shaped drive shaft that slips into the end of the cam called a coupling - item #71 on the diagram p/n 119215. I know because mine was sheared when I took it apart and I had to buy a new one.

 

I for sure thought the roll pins were the shearing mechanism a first. But as I continued to fight my leaking cam end realized that the waist of the barbell is the weak point and replaced my home made pins with roll pins. Right now I have an aluminum piece I turned with a few o-rings on the end and the leak has stopped, but I'm not sure yet that it is my final resolution.

 

Well if you're still running the air pump full time I would say you need a safety of some sort. I could look up the receipt for that coupler I don't think it was that bad, maybe fifty bucks. Maybe you could just put a neck in that aluminum shaft you made to give it a weak link. That would , in essence, be the same as the OEM part, not exactly rocket science.

 

To any one from CARB cruising this forum, yes, I run my smog pump 100% of the time and it would be ridiculous to even consider that it might be on the garage floor right now.

 

Follow-up: Just for future reference in case anybody ever needs it. I went to the hardware store and picked up a couple of sizes and lengths of roll pins (or spring pins, I think Ace had them labeled as security pins) anyway the size that fit perfectly was 5/32 x 1 inch which is about 4.15 mm

Also if you are going to do this I suggest having the pin aligned vertically before tapping it in because if you have it at like a 50-60 deg angle the alignment will be such that the existing pin, as it gets knocked out will wedge itself perfectly between the end plate and the pulley flange such that you'll need to poke around for more tools to get it out - ask me how I know...

 

Is this unique to the QV, or is it true to any cars that are still running an air pump?

 

The 1983 QV air pump setup is unique. No other 308 had the strange shear-able drive to protect the cam belts that I know of. Starting in 1984 the air pumps were no longer part of the emissions system.

 

Good cross-section drawing of the 1983 US 308QV air pump drive in the attached publication:
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(I believe the "safety connection" is intended to shear if the air pump gets frozen, as Paul noted, but that "ring nut" label seems wacky vs the SPC figure. Also, the SPC shows two pins at the end --- one a split spring pin, and the other a solid pin inside it?).

 

Here's a picture of my broken one, cam would be on the left, pulley on the right. I have oriented it with the pin holes aligned for the picture but if I mate the shear point correctly they are 90 deg apart.

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