which temperature sending unit

ok I want to install two temperature sending units on my 1997 Evinrude ocean Pro 90 hp.

I cannot find a listing anyplace for the OMC.,..the thread appears to be a 1/8-27 pipe thread.

there is a threaded opening on each head that is empty.

apparently the factory installed SENSORS but not sending units

I found some sening units from Sierra but they have like 6 different models of the same thread with different OHMs...



and Teleflex makes UNIVERSAL sending units.

how do I know which one is right for my application?

I have a guage already mounted and I have an on -off-on switch to pull the temp singal from either sending unit, once i get them installed, so i can check the temp of each head

thanks

bob

Re: which temperature sending unit

Hi
You have to match your sending units to your gauge. Contact the gauge OEM and check their sending unit specs for your gauge model.

Cheers

Re: which temperature sending unit

I have an red OMC guage from 120 degrees to 220 degrees

bob

Re: which temperature sending unit

That does us no good because we have no idea what the sender resistance is for the senders that go with that gauge. You need to talk to the parts guy at your local Johnny/Rude dealer. But I'm guessing that a 33 - 240 ohm generic sender will be the one you need. However, the actual design of the generic senders may not work in the holes you want to install them. Here are two typical senders. The bronze one must be installed in a port that opens into the water jacket. Or, it can be installed on a special bracket that mounts with a head bolt so the tip of the sender is in direct contact with the head. The silver type is actually a cylinder head temp sender and mounts the same way.

The picture below shows a temp sender (bronze) threaded into the water jacket.

This is a typical cylinder head temp sender but it works with most gauges.
Here is how the gauge should be wired to select which sender you are monitoring.

Re: which temperature sending unit

I was just at a local Johnson-Evinrude dealer...matter fact it was the only J-E dealer on the biggest lake in ct.

and he doesnt carry them and didnt know or want to find out what sender went into that engine...even though he had the same motor as mine in his shop with the cover off and I POINTED to the empty thread and said "it goes RIGHT THERE"

he is not going to stock ANY parts from now on.....just order what ever he needs.

I had also asked him what years lower units inter changed for a friend 48 special....he didnt know and even when i said ,"dont dealers have a cross reference sheet?"


he still didnt care to think about it...EVEN though my buddy just dumped $750 for a motor swap ( both my buddies motors)

so it wasnt like we were asking for info for free....I was taking my buddies OLD motor.


here is a photo of the open thread I think the sender should be going into.

I have been on several parts dealers websites looking for which sender to buy..

and Id buy it from anyone who could sell it to me...but few even list any senders for gauges..

bob

Re: which temperature sending unit

I would use the silver type of sender (33-240 ohms) and mount it under one of the cylinder head bolts. Faria and Teleflex both have outboard temp senders.

Here is what I think you need. But to make it work properly the threads need to match and the tip of the sender MUST contact the bottom of the threaded hole as this becomes a "cylinder head" temp sender with this type of intallation.

http://www.outdoorsuperstore.com/product.asp?prod=268056

Re: which temperature sending unit

thanks....Ill look around at all the marine parts site for a teleflex with the part number for the 1/8th" npt....

bob

Re: which temperature sending unit

Silvertip said:

That does us no good because we have no idea what the sender resistance is for the senders that go with that gauge. You need to talk to the parts guy at your local Johnny/Rude dealer. But I'm guessing that a 33 - 240 ohm generic sender will be the one you need. However, the actual design of the generic senders may not work in the holes you want to install them. Here are two typical senders. The bronze one must be installed in a port that opens into the water jacket. Or, it can be installed on a special bracket that mounts with a head bolt so the tip of the sender is in direct contact with the head. The silver type is actually a cylinder head temp sender and mounts the same way.

The picture below shows a temp sender (bronze) threaded into the water jacket.

This is a typical cylinder head temp sender but it works with most gauges.

Here is how the gauge should be wired to select which sender you are monitoring.

Click to expand...

Can you tell me where I can find a surface mount sending unit? There is not any place on my motor for the screw in type, and I have not been able to find a surface mount in my area. Thanks

Re: which temperature sending unit

Can anyone tell me where I can find a surface mount sending unit like the one shown in Silvertips post on August 15, 2009? There is not any place on my motor for the screw-in type, and I have not been able to find a surface mount in my area. Thanks.