Highest OIl Temps that are safe
05-26-2017, 07:36 AM
#11
Most of me wishes I didn't change the seawater pump this season to the Hardin. I'm changing to many things at one time and then discovering new things which then cause me to wonder what else could be going on. If I never installed the oil temp gauge I would never know my oil was getting to hot, the previous sign was that the oil was getting black quick.
Note, this is a heavy cruiser so the motor is working had all the time
Note, this is a heavy cruiser so the motor is working had all the time
05-26-2017, 07:38 AM
#12
Gold Member
Gold Member
iTrader: (5)
Join Date: Oct 2005
Location: Olmsted Falls,Ohio Marblehead,Oh
Posts: 11,634
Likes: 0
Received 204 Likes
on
132 Posts
Temps before cooler are 220-230? That's normal it seems to me... I was told 230-235 max AFTER cooler is the max... that gives you normally a 50 degree drop...
After build was running 20W50 but was only reading 25 psi and would dip slightly lower when coming off plane. Working with another it was decided this season to try 50W to get the pressure up. Installed a mechanical gauge Tee with the electrical gauge. Found a 15 higher reading with mechanical gauge, so figured a 100 psi sender was installed instead of an 80 psi one. Installed a 80 psi gauge and now the gauge reads within 2 psi of the mechanical.
With the gauge offset issue discovered and pressures running so high I'm changing back to 20W50 before I take it back out. Going to reinstall O2 sensors and measure AFR to determine if this is also an issue.
Reading temps at the filter head before the cooler
The old cooler was 2x15 and the new is 2x21 and looks like this one
[ATTACH=CONFIG]567703[/ATTACH]
With the gauge offset issue discovered and pressures running so high I'm changing back to 20W50 before I take it back out. Going to reinstall O2 sensors and measure AFR to determine if this is also an issue.
Reading temps at the filter head before the cooler
The old cooler was 2x15 and the new is 2x21 and looks like this one
[ATTACH=CONFIG]567703[/ATTACH]
05-26-2017, 07:39 AM
#13
Gold Member
Gold Member
iTrader: (5)
Join Date: Oct 2005
Location: Olmsted Falls,Ohio Marblehead,Oh
Posts: 11,634
Likes: 0
Received 204 Likes
on
132 Posts
Quote to me when I asked about mine from a respected builder on this site
"I read the temp going into the engine. If you read it before the cooler, You are taking the cooler out of the equation. If you have a small cooler, the temps will be higher than if you have a large cooler. I want to know what the bearings are seeing. I don't want to see over 230-235 deg. That would put it near 300 before the cooler. A conventional oil will start to break down at much over that."
"I read the temp going into the engine. If you read it before the cooler, You are taking the cooler out of the equation. If you have a small cooler, the temps will be higher than if you have a large cooler. I want to know what the bearings are seeing. I don't want to see over 230-235 deg. That would put it near 300 before the cooler. A conventional oil will start to break down at much over that."
The following users liked this post:
Cap'm Kurt (09-17-2021)
05-26-2017, 07:45 AM
#15
Registered
iTrader: (3)
Id like to think, that Mercury Racing, has done a little bit of homework on their high dollar engine packages. What their reason is for limiting oil temperature, I dont really know. Whether its life of the oil, cooling of internal engine parts, or what. But for a guy like me, who doesnt have a multi million dollar R&D department, I take some of their recommendations seriously. Definitely would take what they do, over what I read on the interwebs.
05-26-2017, 07:49 AM
#16
If I'm getting a 50 degree drop then 185 sounds good, but this is early season and the water will get much warmer so still need to get my temps down I'm thinking
MT, agree you have much more power and as you say your staying lower then me. Sure hope I don't have to change out the Hardin pump, bad enough to change impeller every other year hanging up side down
MT, agree you have much more power and as you say your staying lower then me. Sure hope I don't have to change out the Hardin pump, bad enough to change impeller every other year hanging up side down
05-26-2017, 07:52 AM
#17
Gold Member
Gold Member
iTrader: (5)
Join Date: Oct 2005
Location: Olmsted Falls,Ohio Marblehead,Oh
Posts: 11,634
Likes: 0
Received 204 Likes
on
132 Posts
Not sure if that was for OP or me, but My info came from Eddie Young just so I don't get bashed for posting what I was informed . In my case in past I would see 150-200 after cooler, but had a hard time in coolerbwater after a richer tube, so I added stats this season now see too much temp, 230 after cooler and climbing... so yesterday inremived them, hence why I asked Eddie his opinion just one of many.
05-26-2017, 09:13 AM
#18
Registered
iTrader: (1)
Oil temps in the pan are the average of the oil temps seen in the motor.
A long time ago, a test was set up with a SBC to measure oil temp at the bearings and various other places. They found that bearing oil temps where 60*F - *75F hotter than the oil temp in the pan.
So, this is why some prefer to measure oil temp in the pan, again because there is a reference to go by using this method.
Bearing material and oils used at the time (I believe before synthetic oil was widely used) where considered and a general guideline of target oil in the pan temps was created + generally agreed upon.
The following charts (engine + trans) are pretty much based off of that.
A long time ago, a test was set up with a SBC to measure oil temp at the bearings and various other places. They found that bearing oil temps where 60*F - *75F hotter than the oil temp in the pan.
So, this is why some prefer to measure oil temp in the pan, again because there is a reference to go by using this method.
Bearing material and oils used at the time (I believe before synthetic oil was widely used) where considered and a general guideline of target oil in the pan temps was created + generally agreed upon.
The following charts (engine + trans) are pretty much based off of that.
05-26-2017, 09:17 AM
#19
Registered
iTrader: (1)
That said, there is reasons why some suggest to read the oil temp after the cooler.
One of the largest reasons why I believe this is / can be important is because of being able to see your oil temp going into the motor when you are going to run the engine at high rpm. Most agree that min oil temp going into engine before running WOT for most motors is 160*F-*180*F.
With just using oil pan temps, you won't know this unless you 100% know what temps your cooler is removing.
One of the largest reasons why I believe this is / can be important is because of being able to see your oil temp going into the motor when you are going to run the engine at high rpm. Most agree that min oil temp going into engine before running WOT for most motors is 160*F-*180*F.
With just using oil pan temps, you won't know this unless you 100% know what temps your cooler is removing.
05-26-2017, 11:31 AM
#20
Appreciate it guys, could figure a way to measure temps after the cooler, but in any case with current temps it appears I have another problem to solve. Just changed the oil to 20W50 and the cold oil pressure is slightly lower then with 50W.
