Johnson 175 wont warm up!!!!!!

[bob johnson]

I got this motor and there were no tstats in it , so I thought it might have an over heat issue...but I installed brand new t stats. and ran the motor...it will not move my temps gauges which start at 120 degrees!. the heads are barley warm to the touch. I am thinking this isn't a desireable situation... I thought water might be getting by the t stats seal so I machined a rod to fit inside and I made sure they seals were round on the id... the springs are good...I ran the idle to 1500 rpms for 10 minutes and still the motor didn't warm up. I cant find my infared thermometer, but I can touch the heads and they are not warming up.. the port is SLIGHLY warmer than the starboard side. last night I cranked the idles screws in all the way and backed out 5 turns per the manual( they were at 6 turns). no change.

last weekend I ran the motor out on the river to 5600 rpms.. the temps didn't budge. water pressure is at 10-15 psi at idle....is it possible that is pushing the t stats off the seat??? the springs are used springs....what else could cause this motor to run so cool...???

Ill add 1997 fast strike ( 60 degree looper V6)

thanks

bob

 

[sutor623]

Bob, when I was having issues with my last head, I bought two freeze plugs from advanced auto and put them in the thermostat holes, and tightened em up. Then I put the therm covers on and started her up. This made SURE that there was no way water was coming into the cylinder heads prematurely. Motor still didnt warm up on the starboard side, so I KNEW it wasnt from water bypassing the thermostat/poppit.

If that helps the motor warm up, Id recommend changing those springs to keep the proper pressure on the grommet.

 

[metriccrescentwrench]

...it will not move my temps gauges which start at 120 degrees!.

All the JohhnyRudes I've owned call for the head temp to be around 125 or so at speed, and 140-ish at idle.

the springs are used springs

I'd be replacing those springs for starters.

 

[oldboat1]

Springs. Might try stretching them out a little, but probably replace. If the t.stat has a slotted gasket, it goes over/around the flange. Couple of different assemblies, I think, so would want to be sure you have the right ones for your model number.

ed. mmm... see the springs are good (guess you had to replace the whole assemblies?)

[btw -- cold running may be the cause of the idling problems mentioned earlier, or a factor.]

 

[bob johnson]

actually a little has gone off in my head.... Ill stretch out the springs for starters....and if that works somewhat, ill buy new springs, but the highlight might be that I finally have a plan to solve my Johnson 115 over heat issue... my other motor a 1995 ocean runner 115 has had port side hot issues at idle running to 180 degrees pretty regularly...never could get a solution for that.....it cools nicely when I run up to 2500 rpm or more!!!( t stats gets PUSHED OPEN)...sooo maybe ill LIGHTEN that T stat spring in the port head of the 115, and see if it lets cool water seep in at idle!!!!! hmmmmm...since I rebuilt the carbs once...I am ruling out a lean over heat condition!!!...I even open the idle a little on those carbs...no change


bob

 

[oldboat1]

gee, I don't think it works that way, though. The spring should hold the t.stat in place, as I understand it. If it's too weak, the whole t.stat moves and lets water by (cold running condition). Let's see, if you take the spring out of the '95 or relieve it's compression, the whole thing might move -- which could have the effect of letting cooling water through when it was previously blocked. Sooo -- might be a partial fix for overheating, but kind of an incidental fix. Think I would remove the thermostat and see if you get cooling (would suspect a t.stat stuck closed). (??) Makes my head hurt.

 

[bob johnson]

gee, I don't think it works that way, though. The spring should hold the t.stat in place, as I understand it. If it's too weak, the whole t.stat moves and lets water by (cold running condition). Let's see, if you take the spring out of the '95 or relieve it's compression, the whole thing might move -- which could have the effect of letting cooling water through when it was previously blocked. Sooo -- might be a partial fix for overheating, but kind of an incidental fix. Think I would remove the thermostat and see if you get cooling (would suspect a t.stat stuck closed). (??) Makes my head hurt.

yeah I chased that over heat on the 115 for years, and just gave up thinking it is a blocked passage somewhere....I have run that 115 without t stats and sure enough the temps don't bump the gauge at all!!! runs cold as can be.... so thinking there maybe be some blockage in the block up around the port cylinder head... but this spring possibly being weak on the 175 and maybe letting water through when it isn't supposed to , got me thinking it could be a test for my 115....

I wouldnt run the motor with out t stats, mainly because the water pressure drops to 5 psi even at WOT....... I doubt my rectifier is getting much cooling at 5 psi!!!!!!!!

bob

 

[oldboat1]

Well, can try relieving the spring pressure and see if you get some cooler running and still maintain water pressure. Think if it runs too hot almost from the git go, it could be a blockage in a bypass passage, but otherwise sounds like the t.stat isn't doing it's job.

Down on the Chesapeake, I'm pretty sure winter fishermen sometimes run without t.stats because of salt water corrosion. I never did much late fall or winter fishing when living down there, so can't speak from experience.

 

[sutor623]

I have experimented with springs and they don't seem to make a huge change in temperatures if you alter them some. I think the stock height of those springs is 1.25". I really would try freeze plugs to block off the thermostats and see if that changes anything............ Just be ready to shut her down!!

 

[emdsapmgr]

Not sure just what your perceived problem is. It is normal to have an engine run at idle in the 140-150 range. As soon as you get on plane, thermostat housings open up and flood the powerhead with tons of extra cooling water. You could see the temps go down 20-30 degrees when this happens, once on plane. If you are in really cold lake water (such as now) you may find the planning temps may not even show anything on the temp gauge. That's normal. So, when are your experiencing the 120 degree temps?

 

[bob johnson]

Not sure just what your perceived problem is. It is normal to have an engine run at idle in the 140-150 range. As soon as you get on plane, thermostat housings open up and flood the powerhead with tons of extra cooling water. You could see the temps go down 20-30 degrees when this happens, once on plane. If you are in really cold lake water (such as now) you may find the planning temps may not even show anything on the temp gauge. That's normal. So, when are your experiencing the 120 degree temps?

I DONT EVEN, experience 120 degrees!!!! the temps NEVER reach 120 at idle nor on plane at wot !!!!!!!! I know 140-150 is normal. Id love to get there!!

I am going out now to stiffen the t stat spring....see if it high water pressure and or a weak spring at idle that letting the head stay cold

bob

 

[emdsapmgr]

A couple more thoughts. There are two thermostats, for the 175 this year, 437090, which is a stat with a plastic cover, 133 degrees and is to be used on models ending with a E" suffix. The other stat is 435491, used on models with a "c" suffix- 143 degrees. The latter stat is just the normal metal one, no plastic shield on it. So, make sure you have the correct stat for your model. Next, that engine should idle in gear at 650 rpms. In neutral, it should idle about 900-950. Both of those idle rpm's should be 8-9 lbs pressure. At that low pressure, likely the engine should heat up normally, if the stats are functioning properly. If you are idling it at 1500, that's way to high, and the excess water pressure from the pump may cause the stats to move away from their seats and flow too much cooling water. Are the stats and springs genuine Bombardier parts?

 

[bob johnson]

OK I am idling at about 900 on muffs in neutral... I started her today ran at 1500 rpm for a few minutes and then set it back to idel...and I heard a few coughs and sputs..I cranked each carb idle jet in 1/4 turn and it smoothed out...don't know if its the adjustment or just the total time warming up... plus I opened the t stat covers and pulled the springs and STRETCHED them to almost double what they were... as it was there was hardly any force on the plastic t stats when I started screwing on the cover originally..... so with the stronger spring force the temps rose in about 5 minutes...eventually settling with the port side at about 130 degrees and the starboard side at about 140...ran another 10 minutes at 1200 rpm.....engine sounded nice.... I don't think the t stat opened at all....

I think the main issue is my water pressure is strong!! at idle I am pumping 15 psi!!! and the springs were weak....

at 1500 it goes to about 18 or 19.... the pump is strong.... I think I may get 10 psi on my ocean runner 115 at idle....

thanks for chimming in..... I really wish I could find my infared temp guage.....but I could still put my hands on each each without getting burned.... so I think the gauges are fine...


bob

 

[oldboat1]

Nice!!

 

[emdsapmgr]

So, I'm still interested in which of the two thermostats you are running. Are you running the cold ones, or the hot ones, based on the model suffix of your engine? Also, are the new springs you are running purchased from Bombardier or are they aftermarket?

 

[bob johnson]

well.... I am running plastic bodied t stats..like I mentioned. I have no idea what the temp range for opening is... I actually bought two new Bombardier t stats that called out for my motor year and model #. part#0435491 is the t stat I bought

 

[Chris1956]

Bob, Your motor is likely to require thermostat seals under the cylinder heads. Maybe your's are missing or damaged?

 

[bob johnson]

no , they are there, and one looks perfect, and one looked a little out of round, so I turned a tapered bar to fit inside and work the ID to make sure it was round and thus seal my t stats as good as possible...put the port seal looks like its brand new... I actually bought two new seals when I got my parts order.... just in case that was an issue....


bob

 

[emdsapmgr]

You have the correct stats. The 491 stat opens then it gets to 143 degrees. My guess the other (colder one) might be for the commercial model..?

 

[Faztbullet]

Check yer pm...