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1996 E90 60 degree V4. Starboard #1 cylinder warmer than Port 2&4- Starboard # 3 overheating over 3Krpm. I appears that cooling enters the heads at the tops of the banks, where thermos are, and exits at the bottoms. I found a small piece of broken shell blocking the pee indicator.So if I have a restriction at the bottom of the head, the upper cylinder heats the incoming water before it gets to the lower. Before taking any action, I shot the cylinder heads at the plugs with an IR thermometer. At idle #2 160, #4 162, #1 165, #3 168. At engagement of S.L.O.W. I shut down and immediately measured #2 168, #4 168, #1 178, #3 192. After sitting 1 minute #3 jumped to 212. Start up & idle and all temps drop to idle temps. I replaced the impeller which had taken a set. I replaced the thermostats. Now idle temps are 130 for cyl 2,4,1 & 150 for cyl #3. So I pull the heads looking for leaking head gaskets & obstructions. Found 1 broken O-ring on each side, but not #3. Found a wee bit of crusty "sand" at the bottom of the 1&3 bank. Blew compressed air- no resistance. Re***emble, run and still engaging SLOW after 1 minute at 3700rpm. Check IR temp & #3 still overheating. Since water takes the path of least resistance, can I remove thermostat on 2&4 and plug the thermo hole-replace the cap, remove the thermostat on 1&3-replace the cap, hook up a hose to the pee indicator fitting(made for this) and use street water pressure to flush out the bottom of the head and return p***age? Can I pour CLR or diluted muriatic acid into the head( being sure not to get it in the theromstat hole) to eat away/loosen sand/shell, then blast it with the street pressure? When I had the head off I could not find any obstruction in it, so it has to be downline from there, but with the head off I could not see any shell or sand in the block.
Can I run it with the theromstat removed from bank 1&3? That might "force" water to the 1`&3 side. With the hose hooked up and thermostat out there is good flow out of the thermostat gasket. With everything installed , pee indicator removed, there is great flow too, but no way to tell which side is releasing the water to the indicator female hose fitting.
I forgot to mention that when I changed the impeller, I found the intake screen below it was falling apart. I replaced it. I presume this is how a tiny piece of broken shell ended up in the pee tube indicator. That is why I poked, prodded, scraped, vacuumed & blew compressed air into the p***ages when I had the heads off.
Today I plugged the 1&3 thermostat seal & vacuumed at the cap fitting -reverse of normal flow. I got no debris. Next I removed the plug and left the thermostat out, and installed the cap. I ran the hose to the indicator fitting and ran water at 80psi for 10 minutes. I reinstalled the thermostat & fired up the motor. After 10 minutes of idle, temps were low (105)& equal at 1&3, 120 at 2&4. I thought the flushing was responsible for the equal & lower temps of 1&3. I idled 10 more minutes to the river and ran at 3Krpm for less than 2 minutes when SLOW engaged. I shut down and measured #3 at 186, #1 at 172 (no longer equal). I removed the thermostat from 1&3 and ran at 3200rpm for about 3 minutes when SLOW engaged. I checked temps at 1&3 (both 162) & 2(186), and 4(162). Apparently releasing more flow to 1&3 means less flow to 2&4. So there is some balancing act to the design of the cooling system. What does not make sense is with 2 new thermo seals & 2 new thermos, the balancing act is out of whack. I suppose I should try vacuum/flushing on 2&4, even though they have never been a problem. And then try swapping thermostats to see if that makes any difference. And I will look to see if torquing the heads distorted the new thermo seals. I hand pressed them into the heads as tight as I could and they were not distorted at that time. What am I overlooking?
Can I run it with the theromstat removed from bank 1&3? That might "force" water to the 1`&3 side. With the hose hooked up and thermostat out there is good flow out of the thermostat gasket. With everything installed , pee indicator removed, there is great flow too, but no way to tell which side is releasing the water to the indicator female hose fitting.I forgot to mention that when I changed the impeller, I found the intake screen below it was falling apart. I replaced it. I presume this is how a tiny piece of broken shell ended up in the pee tube indicator. That is why I poked, prodded, scraped, vacuumed & blew compressed air into the p***ages when I had the heads off.
Today I plugged the 1&3 thermostat seal & vacuumed at the cap fitting -reverse of normal flow. I got no debris. Next I removed the plug and left the thermostat out, and installed the cap. I ran the hose to the indicator fitting and ran water at 80psi for 10 minutes. I reinstalled the thermostat & fired up the motor. After 10 minutes of idle, temps were low (105)& equal at 1&3, 120 at 2&4. I thought the flushing was responsible for the equal & lower temps of 1&3. I idled 10 more minutes to the river and ran at 3Krpm for less than 2 minutes when SLOW engaged. I shut down and measured #3 at 186, #1 at 172 (no longer equal). I removed the thermostat from 1&3 and ran at 3200rpm for about 3 minutes when SLOW engaged. I checked temps at 1&3 (both 162) & 2(186), and 4(162). Apparently releasing more flow to 1&3 means less flow to 2&4. So there is some balancing act to the design of the cooling system. What does not make sense is with 2 new thermo seals & 2 new thermos, the balancing act is out of whack. I suppose I should try vacuum/flushing on 2&4, even though they have never been a problem. And then try swapping thermostats to see if that makes any difference. And I will look to see if torquing the heads distorted the new thermo seals. I hand pressed them into the heads as tight as I could and they were not distorted at that time. What am I overlooking?
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