hunster

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.

Thunderstruck

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.

awsomethunder

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

Thunderstruck

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.

carney

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.

awsomethunder

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?

blue thunder

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

paulkairis

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

awsomethunder

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

bassmek2

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