Oil Temp Too High 250-300
 

why is my oil temp so high.i flushed the cooler,found broken impeller pieces.flushed all the lines.this is a carb 454 mag.it wasn't this high from the factory right? i am using mobile 1 to protect from the high temps but it should be around 220.i cant hold it wide open for more than 30-40 seconds and it sucks.

Back flushed? Bearing clearances? Not enough info.

it was backed flushed,stock motor,20 psi oil press at idle 45 3000 rpm

I just found out I had a faulty circ pump (impeller fell off). I was having high block temperatures as well. May be worth it to pull it off and inspect it for damage or clogs.

just replaced circ pump,new sea pump last year.have plenty of water pressure.could the hose in the transom be bad?

I would check out your T-stat housing. Maybe most of the water is bypassing the engine and going straight to the exhaust. One big thing to check is If the little balls are missing/damaged/springs weak, etc. for the lines running to the exhaust, that may be your problem.

Also, make sure you have the right gasket in the top part of the assembly. There are like 3 different designs that all fit, but you need the correct one for the specific T-stat boss you are running.

well just pulled my oil cooler off and looking down thru the honeycomb passages the 4-5 that are in line with the oil lines were plugged with chit.could this be my problem or should i keep looking.its hard to believe the 4-5 passages plugged could cause this considering theirs 30 or so.just wanted to know if this could be it

That's 16% blockage, if my math is correct, which could be an additional 16% LESS cooling of your oil. I think it may be the issue.

Dave

i was going to suggest removing the end caps if your cooler has them. if sedimented, use a small diameter strand cable in a drill at low speeds to clear.

good luck

and yes those passages , especially if together will raise the temps, kinda like a heat sinc, but in reverse

Engine water temp and oil temps go hand in hand, almost. What temp tstat do you have in the coolant?

i have a 160 t-stat and just ordered a 140.i heard og people drilling 1/8 inch holes in the stat.where do you drill the holes and why.and my thermostat housing has no spring loaded balls at the end.is this a problem?

You drill the hole if you have a crossover. Changing the thermostat to 140 will not accomplish much. It will open at 140 instead of 160. 140 is to cold to be running an N/A engine. What is your current water temp, I read all the postings and never saw it. It started with oil temps to high, and now talkin about water.

water temp is 150-160.if i can lower water temp won't it lower oil temp also?

Some of your increased oil temp is probably due to your motor running leaner due to the ethanol in the fuel. You need to increase jet sizes or change metering rods depending on what carb you have.

Maybe your cooler is rigged like mine was?:(

liquid tell me you are joking

Back to your problem, it is only high oil temp?
What temp did the oil run before?

If it jumped from 220 to 300 there is a problem and I don't think you are going to find it in the oil cooler, you might want to cut open your oil filter and see if there is any metal in there. That would cause high oil temps:(

The blocked tubes also speed up the water through the rest of the cooler, making it that much less efficient.

No joke here...that is what we found when we pulled the motor!! The fuel cooler was as big a mess. Classic case of buyer beware.

my temps have always been high since i bought the boat last year.found impeller pieces in cooler last year and it seemed like it took longer to get hot after i backed flushed the cooler.when i replaced the sea pump all i replaced was the impeller.should i replace the plastic housing and wear plate too?have good water psi.my sender is in the filter housing before it goes thru the cooler.

What where your oil temps last year?

What is your current engine temp?

As a rule of thumb you usually replace the housing and plate on the seawater pump. Its not that much more. If you have good pressure you will be fine.

Try the 140f tstat. You may be suprised at the drop in oil temp. There is a direct correlation from my experience.

BT :cool:

my oil temps last year were the same as they are now,water temp is 160-180.i was thinking if the water temp is down with the lower t-stat the oil temp will drop also

my stock t-stat housing has no spring loaded check balls.is this normal?

I run my engines at 135-140 coolant just for the purpose of keeping the oil temps under 230f. I've done everything imaginable to get the oil temps right, but this is the only thing that made it so I can run hard for long periods of time. I used to be like you. 30 second shot then crack the hatch and let the oil temp drop. I even wiped out the mains on the sb engine one summer when I let temps get up to and over 300f. I have had no ill affects from running my engines at this coolant temp. They look great inside. This will be my 3rd summer running on this build and with the coolant and oil temps inline.

Pretty sure thats your problem. Check to see if yours is supposed to have them. If it is supposed to and doesn't, most of the water will bypass the engine and go straight to the exhaust.

I had a circ pump fail, and it had roughly the same effect.

how do i know if i should have the check balls?and if they were there why would they be missing

Look up your motor here and then click on thermostat or cooling when you get that far. They have the exploded views of the original merc manuals.

http://www.mercruiserparts.com/selec....asp?type_id=8

What he said . Check your plugs! What color are they? I found my sb's running lean after the switch to the ethanol. Upped the jets and metering rods 2 #'s , run 1 heat range cooler plugs. We'll see. I had 40-45 oil pressure when cold and after a short wot blast , 15-20 lbs pressure. Looked at the plugs and they were white! :eek: Hopefully now I'll see that nice golden brown!:cool:

now you guys got me woried about the ethanol thing.if i need metering rods where do i get them?and where are the jets on these carbs.had lots of holleys apart but never a q-jet

Not sure on the q-jets either , I have the webers , like the new edelbrocks. Your local speed shop should be able to get you a jet kit or just the specific jets. Check your plugs , if its lean , the tips will be white! , you want a nice light brown color. Look at the ngk site , they have a good set of pics that the plugs should look like.

Could you clarify your post regarding the water Pressure?? You said it is measured at the filter before the cooler. Are you sure this is water pressure?? My water pressure measurement is a mechanical gauge on top of the tstat housing.

Anyway, you need to check the water hose fitting that comes through the transom assembly. the hose gets squeezed from corrosion and starts limiting water flow. The first symptom is higher than desired oil temps. Happened to my Thunder on both motors. Wallowed out the holes, replaced the hose inserts and fixed.

Sounds like you have covered most of the obvious stuff.

thunder my oil sender is at the filter before the cooler.to look at the transom hose i need to pull the drive and gimbal ring correct?i will splash this weekend to see if cleaning the cooler and lower t-stat helped.if not i will look into the transom hose.just so i know i should have no overheat or oil temp issues holding wot for 3-5 min right?or even 3-4000 rpms.my oil temps come up at cruising rpm not just wot

No you shouldn't have high oil temps from 3-5 min at WOT or a fast cruise.

You need to take the hose barb off of the transom assembly on the inside of the boat. The transom end of the water pump suction hose. This is tight as it is just above the drive shaft to starboard. Maybe you can remove the stbd exhaust if you can't get to it. The hose is inserted through the transom assembly from the outside. An insert is threaded into the hose to seal it inside the hole in the transom assembly. Then the hose barb is bolted to the transom assembly. The hose barb covers the water hose and can let water get onto the aluminum which compresses the hose and insert. It doesn't take much to restrict the water flow on the suction side of the pump.

It is a job with the motor in the boat.

I just went through the same problem. If your boat has a black alum housing that the oil filter screws to there is a t-stat in the housing for the oil temp only. the part cost 20.00 and takes 20 min to change. this fixed mine.

is this t-stat in the adapter on the block that the hoses come out from or where the filter screws on in the front of the motor?

I don't agree with oil not heating up after 5 mins of WOT. That is a lot for a bbc. You need to be on you gages for sure if you are doing that. Cruise it should plateu under 230 and stay there. Cruise is 3500 or less in my opinion.

BT :cool:

Hello, i find this line of ??ing interesting because i have the same hot oil problem with my motified 502 although in my case i beleave it comes from worn out bearings, cuz i have no oil pressure at idle do to the fact that the previose owner new nothing about carbs and let the 1050 dominater totaly dalute the oil with gas. don't even get me started on that guy. i'd like to here more from bob 280 or anyone about bearing wear and clearances and hot oil temps. and is this the right forum to ask about new bearing manufacturers and carb sizing for a 625+ hp 502 i've dumped the 1050 for a double pumper 850cfm and it runs like a dream but i lost 4 mph on the top end?? also i'd like to hear more about the t-stat in my oil filter relocate bracket, sounds like a no brainer swap out weather its to blame or not?? Thanks Paul 26v Profile

well ran the boat with the new 140 t-stat and cleaned cooler.had 150 water temp and oil never went above 260 on the hard long runs.i still think the oil temp is alittle high but i'll take 260 over 300 anyday.i do use mobile 1 so i think 260 is ok.what do you guys think.thanks for all the help

i dunno if i should post this in here but since u guys are talkin about oil temps i guess i will ....ok here we go i have a mercruiser 502 efi 525 now i changed the inpeller i have good water flow my water temp only hits about 160 max my oil temp i only let it get just above 200 say about 215 and my oil presure drops to about 25/30 somewhere in that area...this isnt my boat im looking at it for someone but im not much of a boat mech and didnt kno what the temps or preasures should be with this motor ....ok i checked both coolers they seem pretty clean i took out the oil thremostat and am running it like that im juss not sure what the temps should be running or what is to high and one more ? how many impellers does this boat have ??? 502 mercruiser stern drive with a bravo 1 xr and xr sport master im not really sure if thats right ill try to get more infor for u guys if u need and im sorta new to forums so excuse me if i did this all wrong thanx for any suggestions and help can contact me on bassmek2 on aim thanx again for any help when my temps were getting to a lil over 200 i got the buzzer also but have no clue if it was cuz the oil or something else ...if my timing was off would i get a buzzer ?? cuz i messed with timing and she ran a hell of alot better and no buzzer this time