Testing overheating issue with t-stats removed?

[jrem]

I finally removed the old t-stats from my Johnson 115hp V4 (crossflow)and it had a lot of "calcium deposit like" grit inside.<br /><br />I'd like to do two things before installing the new t-stat kit I have.<br /><br />1) I would like to run the motor without the t-stats just long enough to see if the temp alarm still goes off (original problem see previous posts). <br /><br />When putting the assembly back together without the t-stats, Do I still have to put the white plastic valves and springs back in?<br /><br /><br />2) I would also like to run some CLR through the cooling system in an attempt to clean out some of the deposits BEFORE i put the new t-stats in so they don't get mucked up. <br /><br />Any thoughts on this?

 

[ezeke]

Re: Testing overheating issue with t-stats removed?

Lots of 115 crossflows have been run for years without thermostats. It isn't good for them, and they don't run right, but it is hardly ever fatal either. Anyway, I would find it unlikely in the extreme that flushing the system by removing the thermostats temporarily did any harm whatsoever.<br /><br />I don't think I'd put anything as caustic as plumbers helper in there. You could put the motor in a barrel like those light green ones that landscapers use and just run it up to say 1,000 RPM. Just make sure you are out of gear or you will be short one barrel PDQ.<br /><br />I got yelled at here for suggesting dishwasher detergent because it cuts grease and scale, doesn't foam, and because I use it myself, so I won't tell you that you should try it.

 

[reeldutch]

Re: Testing overheating issue with t-stats removed?

you can run the engine without the springs and valves.<br />it will run not so smooth and will run cold.<br />not efficient.<br /><br />i would take the heads of and put new waterflow deflectors in. the middle ones can swell up and block water pasage to the bottem cylinders.<br /><br />also i would take the headcovers off and clean the salt out you will be happy you did.<br />there is always a lot of crud buildup in the heads.<br /><br />just be careful taking the headcover bolts out.<br />use heat.<br /><br />good luck

 

[ezeke]

Re: Testing overheating issue with t-stats removed?

BTW: You can run in fast idle for the flushing and testing. The motors with Quick Start systems need around 140 degrees to come out of the fast idle start mode though, so you can't really run them correctly without the thermostats.<br /><br />Just to back up, The suggestions that reeldutch has made are the right way to do it when you have time.

 

[jrem]

Re: Testing overheating issue with t-stats removed?

REELDUTCH - My intention was to just run without the t-stats once so I could more or less confirm that they were the cause of the overheat alarm. But your right, I'm gonna order the gasket kits and go ahead and pull the head covers and check/change the deflectors.<br /><br />EZEKE - Yeah, I'm thinking CLR might be a tad strong. Upon further inspection, the deposits weren't that bad and flaked of easily. The parts I can't clean directly will probably flush out anyway. Your idea with the dishwasher detegent make sense, even if it isn't suggested.<br /><br />Thanks a lot to both of you for your replies, they were definitely helpful. This site is great! I've learned more from these forums than any other source including the tech manuals.

 

[ledgefinder]

Re: Testing overheating issue with t-stats removed?

For testing, if you simply disconnect the two hoses leading from the heads to the thermostat block, it'll have the same effect as no thermostat(s). <br /><br />The system works differently than that in a car. The thermostat(s) 'bleeds' off hot water when the motor gets too hot, otherwise the water just recycles down to the pump & back. When you take the hoses off, all the intake water is fresh cold water. You need all the valves for it to work (not just right - at all). I wouldn't worry about running without thermostats.

 

[rodbolt]

Re: Testing overheating issue with t-stats removed?

the t-stats and little white valves are an intragal part of the water pressure control system and without it it wont work correctly. the water in the motors with twin Tstats and vaves does not recirculate like the older vernatherm models.<br />a common problem,especially with non-vented t-stats is the block gets hot before the hot water goes down to the tstats as hot stuff would rather go up. usually if you increase the size of the bypass hole in the tstat block it will work better. <br />on some of the cross flow motors ,especially with jet drives, that live in the sand I will cut the poppet off and install just the t-stat body so at planing speeds the temp will come up a bit. but no t-stst will rapidly clog the intake recirc check valves and crate other issues.<br /> why not just fix it correctly as designed and enjoy the motor ?