'89 Johnson 70 thermostat questions

[Lowranger]

J70TLCEM, Having gained some confidence from my water-pump replacement I now turn my attention to the thermostat. Searching the topic I find that some consider its replacement a part of routine maintence. My records show that it was replaced in '95. Questions; 1)Shall I test it in a pan of water or simply replace it? 2) Which components need replacing? There is a Vernatherm(0394411) and its spring inside of a thermostat assembly(434137). When purchasing my parts, is the thermostat assembly simply an empty housing or is the Vernatherm and its spring included? There is also a relief valve spring(333858), a valve seat cup(330273), and a valve seat(320880). Which of the other components need replacing? Also, I've read posts here that describe modifying the thermostat by "notching" one of its components. Can someone describe the procedure and its purpose?

 

[c903]

Re: '89 Johnson 70 thermostat questions

No more than a "complete" thermostat kit cost, which includes the thermostat, the housing gasket and the thermo seal, I would replace the entire thermostat.<br /><br />You can get some good buys on eBay for many OB's. I have been refurbishing a 1974 Evinrude 70 hp and have purchased thermo kit and water pump kit from a marine parts supplier for a total of $57.00. Parts are OMC and not foreign, at least the ones I have purchased.<br /><br />If the pressure valves are not damaged or frozen, I would clean them and reinstall.

 

[Lowranger]

Re: '89 Johnson 70 thermostat questions

I apologize for for not clearly stating my question. Does thermostat assembly(434137) contain EVERYTHING I need or are there other parts needed? AND, I've read posts here that describe modifying the thermostat by "notching" one of its components. Can someone describe the procedure and its purpose?

 

[DumbBass]

Re: '89 Johnson 70 thermostat questions

Lowranger, I have an 89 60 HP Johnson and usually replace the entire thermostat. As stated above, the "kit" contains everything you.

 

[Lowranger]

Re: '89 Johnson 70 thermostat questions

HI DB, I appreciate your response. I take it you mean thermostat assembly(434137). The reason I'm confused is that the exploded diagram on Ishopmarine shows the assembly as one part # and seperate part #s for the vernatherm and its spring. I was left wondering if the assembly was nothing more than an empty shell(housing). Also, since you didn't address the modifications I mentioned I take it you don't believe they apply to our motors. If other readers can shed some light here I'd be grateful.

 

[Lowranger]

Re: '89 Johnson 70 thermostat questions

This schematic may help explain my uncertainty. web page

 

[DHPMARINE]

Re: '89 Johnson 70 thermostat questions

lowranger, #37 is just the shell that holds the veratherm.This is because arrows point at them.If #37 was an assembly,a bracket would be shown. [Long line over parts included.] ]<br /><br />DHP

 

[OBJ]

Re: '89 Johnson 70 thermostat questions

The t-stat assembly comes just as that, an assembly. With the new assembly, PN 434137. you can't take it apart as shown in the exploded view. And I do believe a new seat comes with the kit.

 

[Lowranger]

Re: '89 Johnson 70 thermostat questions

Thank you all for your thoughtful responses. This site and its wonderful members have enhanced my Johnson Outboard experience. My 70 and 15 just clicked over 16 years and I couldn't be happier with my motors. I look forward to many more years of dependable service with the help of this site.