Re: 87 85hp Suzuki overheats only WOT Update (A Cautionary Tale)
Just an update on this motor. A cautionary tale for some of us who are too quick to start ripping into these motors. (Alas, this may pertain to me!) After I replaced the head gasket on this motor I did in fact find some severe blockages due to salt and corrosion and I thought I had it fixed.<br /><br />I found the thermostat was now stuck closed when I test drove it. The thermostat had been recently replaced and I had a another post here about whether I should put it back in because it was running good without it and not overheating, although the water was as cold (60 deg F) as it ever gets here. I took the advice to put a new one back in. Well,a s the water temps rose into the 70's here the alarm would go back off after about 3-5 minutes of WOT.<br /><br />I decided to put a temp gage on the cylinder head to monitor the temp. It looked like the alarm was going off at about 190 F.(about 1/3 way between 170 and 220 F). Alas, when installing the temp gage, which uses the head bolt, I stripped the head bolt and had to remove the head again, install some heli-coils and replace the head gasket (again).<br /><br />I decided I needed to pull the exhaust cover and check for blockages there, as it was the only place left I hadn't visualized or already replaced. Because 8 of 15 bolts broke off in the removal process (another post here), I had to remove the power head. I did find some coolant blockages in the exhaust cover passages also, although not as bad as the head was. After I got it reassembled and test drove it, the alarm was still there after about 3-5 minutes of WOT. The alarm was still going off about 190 F.<br /><br />Someone (roscoe, I shoulda listened to you brother) in my "thermostat keep or go" post had suggested that the sensor might be bad and should be replaced. Because it had seemed to be doing its job and was consistent (i.e. it wasn't on all the time or at odd times, only at WOT) I had assumed (ass-u-me) that it must have been OK.<br /><br />Because there was nothing else left, I bit the bullet and called Brownspoint, an online dealer who told me that the sensor should turn on at 237 F and then go off after dropping to 194 F. Since my warning seemed to start at about 190 F I decided to spend the $55.00 for the new thimbal sized sensor and installed it. Four trips later and long periods at WOT I have not heard the warning buzzer.<br /><br />Although I did find significant blockage in the head and some in the exhaust cover passages, one wonders whether replacing the sensor early on might have saved considerable time and money. On the plus side I have gotten really good at removing stuck bolts and my motor pisses like a 2 year old. Just remember wherever you go, there you are.
