camshaft sensor ?

[blipmode188]

I have a general question about the camshaft sensor for the 86 and 87 GN's.

I was searching for a back up to have, simply as a spare and quickly realized that they are very hard to find.

There seems to be a very limited supply and I am wondering what usually fails on them.

I found a replacement camshaft sensor cap on GBODY's site, but am wondering if the main body also fails.

I have no idea why these parts are so difficulty to come by ?
Also what is their general failure mode ?
Is it the cap, or the main body that fails most often or both ?

Im sure there are reasons for them to be hard to come by considering the age of these cars
but since this part can shut down your engine Im guessing at anytime, seems kind of risky not
to have a spare one on hand.

Thanks Steve

 

[Turbo6inKY]

The cap can get cooked and the resin can crack, and if water gets into the hall effect sensor, it can fail. Or you break the wires off so close to the housing that you can't solder a new lead on. Outside of that, they don't fail. They can't. A hall effect sensor is a magnet and a coil of wire. That doesn't go bad unless you cook it.

The mechanical part of the sensor is a mechanical part. It can wear out, but it takes a long time. LIke hundreds of thousands of miles. It turns at 1/2 crank speed and there's no substantial load on the assembly, so it'll last a good while. On top of that, as long as the window in the tooth trips the sensor anywhere from ~18-30 degrees ATDC, then the car's going to run fine, so there's a lot of tolerance for mechanical slop there before it needs to be replaced.

Hence the dearth of replacements. They don't go bad, so there's no market for a reman company to pick them up. If you find a particularly sloppy one, send it to GNS or somebody that rebuilds them.

If they ever start failing en-masse and a market for replacements is created, it's not terribly difficult to cut the head off a distributor and turn it into a new sensor if you have access to a lathe, and several people still make distributors for this engine architecture. So that's plan B.

 

[blipmode188]

Thanks for the reply and info !
Learned a lot from it.
Thanks again Steve

 

[Anthony P]

you might want to forget gbody's site...you can buy the cap direct from Casper's for much better pricing plus free shipping. And the family that owns Casper's is first class...

Cam Sensor Cap Only 1984 / 1989

Cam Sensor Cap Only 1984 / 1989 New design provides a simple and accurate procedure to set the required 25 degree ATDC cam sensor signal. Has built-in LED which indicates an exact setting point. You simply rotate your engine to Top Dead Center and this cap does the rest. No need to index your crank

www.casperselectronics.com

 

[Haynesie]

Its much easier to find the new style cap (with the LED) than the old style cap. The new style cap doesn't work well with the after market ignition system (ie Bob Baileys). If you need the original cap, there are folks on here that will sell you a NOS, but they are not cheap. If you plan on staying with the original ignition, then just get the LED cap, it will last a while and is pretty handy to set (in the event you ever need to do so).

 

[blipmode188]

Thanks to everyone for the info.

I ordered the cap from Caspers to have an emergency spare.
My set up is all pretty stock so hopefully it will work in a pinch,
and double hopefully I will never need it.

Again thanks to all !
Steve

 

[Mr.Spool]

Also they can breaking if over spun

 

[Chuck Leeper]

No experience with BBB.
Does the big block use the same distributor design as the v sicks, NA engine?

 

[turbodave231]

It turns at 1/2 crank speed and there's no substantial load on the assembly, so it'll last a good while.

I respectfully disagree with your statement. Yes, it turns at half crank speed, but there is a load on the unit that you did not consider. This part drives the oil pump. That load causes wear on the gear and the bushings.

This load increases dramatically when using a High Volume front cover or the High Volume gear kit. I have rebuilt several engines that had EXTREME wear on the lower gear and the thrust face of the block where the camshaft rides on the block. All of these engines were using HV pumps. The cam sensor drives were basically scrap and blocks needed considerable machine work to save them.

For a stock engine using 10W30 oil, the sensor will last a good long time........Heavy weight oil, tighter tolerances on the pump, and High Volume gears (not to mention any misalignment due to machining tolerances on the cover itself) all raise the load on the bushings and gear to the point that wear becomes a concern.

Here is how I fixed the blocks:
Machined for thrust washer
Thrust washer installed

 

[Mr.Spool]

The gear does wear over time
All mechanical parts will wear down.

 

[Turbo6inKY]

I respectfully disagree with your statement. Yes, it turns at half crank speed, but there is a load on the unit that you did not consider. This part drives the oil pump. That load causes wear on the gear and the bushings.

This load increases dramatically when using a High Volume front cover or the High Volume gear kit. I have rebuilt several engines that had EXTREME wear on the lower gear and the thrust face of the block where the camshaft rides on the block. All of these engines were using HV pumps. The cam sensor drives were basically scrap and blocks needed considerable machine work to save them.

For a stock engine using 10W30 oil, the sensor will last a good long time........Heavy weight oil, tighter tolerances on the pump, and High Volume gears (not to mention any misalignment due to machining tolerances on the cover itself) all raise the load on the bushings and gear to the point that wear becomes a concern.

Here is how I fixed the blocks:
Machined for thrust washer
Thrust washer installed

Yet another reason 99.9% of engines don't need and shouldn't use a high volume pump.