Carb HP500 Oil Overheating?
 

Water Presure is at 20psi just like port eng, Water temp is 130 degrees just like Port eng but Oil temp stays at about 220-230 at cruise and got up to 280 at full throttle. I immediately came to idle and it went back down to 220. Port eng never gets above 180 degrees. Where should i start to look for this issue? Sticking Thermostat? Trash clogging water impeller pump? Any help would be appreciated. Also, I just had the oil changed and since it got up to 280, do you think the oil is now bad?

Thanks.

I would check the water flow out the back of your pipes and compare it to the other engine. See if the flow looks the same. Next, check water pump impeller. If you have missing blades, then you most likely have some rubber clogging up your flow. I had that happen and I had to back flush it with a water hose to get the rubber pieces out. If all looks good, replace thermostat or take it out. I don't run a thermostat. Make sure your oil pressure is good. By the way, my water temp does not get over 100, but my engines run about 230-240 degrees. 280 degrees too hot. I would change oil if you find the problem.

Verify it is actually hotter with a laser thermometer. Could be a bad sending unit.

would the water pressure gauge still show 20psi on both motors if a blade was broke off the impeller and clogged? Where/how easy is it to check for this and clogging? also, so i can just take the thermostat all the way out and it just stays as cold as possible? thx.

My first guess would be a lean condition. You might swap carbs side to side to see if the issue follows. Also validate timing at 3500rpm.

Your water pressure on both engines showing 20psi kind of throws me off. It does not hurt to check it. You have to take your waterpump off, open it and check it. I assume you have the external belt driven mercury water pump. At that point, you might as well replace the impeller. If any blades are missing, they are somewhere down stream. I was told there is an inline screen that suppose to catch rubber so they don't get clogged in the engine block, but I could not find one on my boat. I followed the hoses to the last point I could reach and find down stream, opened up the hose and blasted it with a waterhose and pieces of rubber came out where I had the water pump taken off. If you ran your boat on the trailer dry, you may have a damaged water pump impeller. Some people think it is OK to run their engine at 4000+rpm on the trailer with a water hose. Don't do that.

First thing is to verify the oil temps.
It could be that the oil is not circulating/flowing through the oil cooler adequately.

He says his water temp stays the same only oil goes up. So water flow ok. Oil filter may have collapsed. Or doesnt flow enough. What else was done? Doubt bad sender since it wouldn't work at all unless its loose.

Does that motor run an oil thermostat? Water goes to oil cooler first sO motor thermostat would make no difference if water temp stays at 130.

I would take out the thermostat and try it. They don't last forever.

Check the oil thermostat on the remote filter pad. If it's stuck it won't route oil to the cooler. Mine was stuck, all I had to do was clean it and it works fine now.

Since water temps are fine I wouldn't think water pump is the problem.

is the thermostat right on top of the intake at the front where all those hoses go? Here is one of my motors. just not sure exactly where T-Stat is.
[IMG]http://img64.imageshack.us/img64/4861/motoro.jpg Uploaded with ImageShack.us[/IMG]

I dont think it's impellers either. they were done at end of last season. boat is never started out of water... with or without water hose. Where is this remote filter pad thermostat??

Its not shown in your pic but should be a sandwich tstat mounting between the oil filter and remote filter mount on the back of the port head.

Oh yeah and one trip to 280f on synthetic oil I would not change it. Dino oil I would.

great info. so there is just one thermostat for both engines? is this easy to get to? Here's a better pic of both motors where you can see the filter of the Port eng.
http://img101.imageshack.us/img101/6...sandlatham.jpg

Uploaded with ImageShack.us

+1...easy test

It's kinda hiding in this pic. Black thing behind the oil lines that go the oil cooler. It has a snap ring that pops out, and the thermostat is underneath it. Just pull it out, clean it, then test it in some hot water and you'll see it expand.

It's worth a shot :drink:

http://i802.photobucket.com/albums/y...p/Motor143.jpg

Oh i see.

so where is this black box thats in ur pics located? directly above the oil filter?

The pic is of the remote oil filter pad. On the back of the engine, port side (where your oil filter goes on). the lines sticking up in the air in the pic are actually facing towards the starboard side of the engine, and connecting to the oil cooler.

You do understand I'm talking about the oil cooler thermostat and not the engine water thermostat right?

This filter pad is mounted to the back of the port side head. NOT down where the original oil filter would go if it was in a car...

Got it. thanks for clarification. will try that first. any idea where water t-stat is?

Its on the front of the intake manifold and under your lifting ring. No need to go there though, its working fine.

X2

sounds like the relieve valve in the block hung open and not sending the oil thru cooler..or still has 11psi relief valve in there

Not engine thermostat people stop saying that. When your ac goes out you don't fix the furnace. OIL Thermostat. And lean wouldn't really do it either only other thing too much timing or dist gear out.

Why is nobody mentioning the obvious...at 280 degrees your buzzer alarms would be screaming. Are they going off? Take the ground off the gauge and check it with the motor running.
First make sure your alarams work by turning the key to the on position (don't start it) and within 5 second or so you will hear an alarm go off.
Also, maybe the needle/gauge is stuck. I still say bad ground like when a tach doesn't read right. Try tapping on the gauge when it hot to see if it moves at all. Sounds like simple fix if your alarms aren't going off.
Try the basic stuff first before you start pulling coolers, filters and thermostats off the motor.

Oil temp... 280 degrees of oil temp... Theres no alarm for oil temp.

Whole lotta confusion going on in this thread... Water vs. oil.

:lolhit:

agreed.

I would start with a new filter first. I have seen them collapse at high rpms.

There are alarms on oil temps, check around.

Not in any stock HP500 carb engine there isn't.

Lean will do it fast. Makes the pistons hot.

I'm pretty sure I have a bad gauge or gauge connection. The eng oil seem like it should have got a little burnt or darker color but still looks like honey. I'm going to put a temperature laser on the oil filter and a few other places to confirm.

Any chance you could just swap sensors between the engines? Or an easier check might be to swap the wire connections - you could probably fab up a couple of extensions from some wire and solderless terminals. If the other gauge starts reading high, you have isolated your problem to the sender. However, it's unusual for a sender to go bad like that. Laser temp gun might tell you something, but it can give a false reading as well. Maybe you could get a comparative reading between the two engines. Point it at each oil pan, and see if you get a significantly higher reading.

carb HP500 oil temp very high
 

carb HP500..do these engines come with oil thermostats? if so, where are they located? I have good water temp, good oil pressure, just oi temp goes high quickly, other motors run cool oil temps??

did you ever find your high oil temp issue solution?? I am having the same issue with one of my HP500's

OLD thread... but having similar issue, if the oil t stat sticks closed can someone confirm the oil is not sent through the cooler ? & result in high oil temp?

Yes and yes, and if you remove it oil dead heads in the cooler. So you have to have a good functioning tstat in that housing.

x2.

ok, thanks guys... the t stat had some crud on it, I ordered a new one.. but may not have in time for the weekend , I did clean up the old one & it now expands in a pot of boiling water .. should get me by for now