OMC Temperature Switch Removal 1986 Johnson 150HP

[Terrapin]

Johnson 150 HP, 1986, Model: J150TXCDC

1. How do I remove the Cylinder Head Temperature Switches from each head? They are functional, but I want to remover them to have my head milled flat. I removed the head cover, and loosened broke the rubber grommet free with PB Blaster, but I am unable to remove the sensor at the bottom of the counterbore. The OMC service manual suggests OMC Gasket Sealant to install. Is there a solvent or a trick to removing them? I picked all of the sealant away from the top of the sensor disc, but they won't budge.

2. I already broke the tan wire off one sensor that was functional. I identified an OMC p/n 386686, is this p/n correct? I have a single tan lead on mine with a knife connector. This p/n on line appears to be two leads (one ground) and a different connector.

Guidance appreciated.

 

[Joe Reeves]

The part number of 386686 is correct for the single wire heat sensor.

With the plate cover removed from the cylinder head, it is a simple matter of just prying the sensors out. If they are stuck, jammed solid with corrosion, then it becomes a trial and error scenario... usually and unfortunately resulting in the destruction of the sensor.

When installing the sensor, I advise simply to install it... put nothing on it.

 

[Terrapin]

Joe, Thanks for your guidance on installation and for confirming the correct part number.

Is there any chance you have a source for purchasing this part number? It seems they are no longer manufactured.

Thanks in advance for any guidance you can provide.

 

[Joe Reeves]

I had a bunch of them left in my inventory when I retired but I sold out of them rather quickly. I wasn't aware that they were no longer available... and I think that rather odd. Scout around the dealerships and outboard repair shops... there's bound to be a few hundred of them there in used heads and blown engines.

 

[Faztbullet]

Don't have more than .015 removed from head....

 

[Terrapin]

Thanks Joe, I noticed in past threads you were selling some and thought I would ask. I'll keep looking.

Faztbullet, I just had .008" removed to clean & flatten the head up. So if I understand correctly, I use the cylinder head gasket dry (no OMC Gasket Sealant), and coat the cylinder head bolts threads with OMC Gasket Sealant? Also, the Cover Plate gasket gets OMC Gasket Sealant, and the threads are coated with OMC Gasket Sealant. Please confirm, the OMC Manual I have is not clear on using the OMC Thread Sealant on the machine screw threads.

Thank you,