Every now and then a problem will surface that is so small that it almost doesn't warrent concern. THIS IS NOT THAT TIME. I feel like an idiot asking this but I must anyways. I replaced the stock 305 in my T/A with a newer 350 from a chevy caprice. The newer engine has an additional plug hole that it an inch or two above the regular drain plug hole. It is about 1 1/2" in diameter, maybe larger. When I first started the engine up, the oil pressure was through the roof. After a week or two of tests and tuning, I noticed a leak from under the engine coming from the location of the unidentified "hole". I looked closer to see that the plastic plug that was once in place had nearly desentigrated into nothing more than a thin coating around the threads. I have asked others for input, but unfortunately, everyone scratches THEIR head and looks at me as though I have two of them. Not much is known of the engine except it was bought from a local police auction when they auction off their vehicles. I am told it had about 60,000-70,000 miles when it was pulled (tax dollars at work, they replace them every few years whether needed or not.) Can anyone tell me what this extra is for?
Thanks

 

Welcome to TGO!

Depending on what year Caprice 350 was from, the hole was probably for an oil level sensor.

 

Where is this 1.5" hole?

 

 

There is a hole above the drain, or CTS in the head?

 

If you are looking at the oil pan, it will be about about 2 inches +/-above the hole for the oil drain plug at the base of the oil pan. The engine is either a 92 or 93 based on the date code.

Stekman, if it is in deed an oil level sensor, would you be aware of any kind of filler plug that is made to be placed into it when it is not in use.

I have tried various sizes bolts to simply fill it in with. However, not even LOWE's or Depot carries one large enough to fit it in the correct thread pattern.

Thanks.

 

maybe look into getting a new oil pan with out the mystery hole in it and replaceing it .....

thats a pain in the *** but it might be your only resolution

 

Turns out you were right. I did some more research and crossed reference the oil level sensor with the engine and sure enough, HOME RUN! Here's a link to the picture if anyone wants to see what I'm talking about

http://shbox.com/1/low_oil_sensor.jpg

Sometimes seeing helps. It appears they started making this in 1993 and used the same design through at least 1997.

Thanks for the help.

 

so now you just need to buy a sensor used or new and put it in the hole and your done then right ?