1975 Merc 500 tattle tale question

[oba97]

I have a 1975 Merc 500 that I got from my in-laws. It has sat for about 5 yrs and when I cranked it, it started right up. I did have muffs on it with water on full, but no water came out of the tattle tale. Is there a thermostat that will stop water from flowing when first started or should I have seen water right away? I shut it off after about 10 seconds as I didnt want to ruin the motor. Any help would be great....the serial number is 4284039

 

[Chinewalker]

It may take a good 10-15 seconds for water to circulate through and fill the block enough to run out the tell-tale. There is no thermostat on those old 50s. If the motor is new to you with unknown service history, it is common practice to install a new water pump impeller as a matter of course. Cheap insurance and not too bad of a job on those, either. Also, check the tell tale for blockage. You should be able to blow back through the outlet.

 

[oba97]

ok, thanks for the info.