February 27, 200917 yr The vehicle in question is a 1986 GL Wagon, EA82, 5 speed w/ dual range, and 190k on the ticker. So my car has been running kinda warm lately, like the needle on the gauge goes from the cold to touching the bottom edge of the red as soon as it warms up and then stays there. The only Idea i've got is maybe a sticking thermostat? I thought that it was maybe the lights I had installed on the front of the car blocking air flow to the radiator but I'm negating that since they're really not THAT big of lights. And the other thing is my oil pressure has gone all weird too. The gauge reads fine until the car warms up, then the temp gauge jumps up as described above, and the oil pressure gauge drops. Anybody got any ideas wtf is wrong with my car?
February 27, 200917 yr when the car overheats you oil will thin out giving you low oil pressure its a cause and effect thing
February 27, 200917 yr It's pretty normal for the oil pressure to read way low, the sending units do that when they get old. As for the overheating, have you checked and made sure the rad is topped off? If it's full of coolant then it probably does have a sticking t-stat. Just to warn you... the EA82s when overheated will let you down later on down the road. You might want to go ahead and just do the headgaskets and have the heads pressure tested to make sure they're not cracked. Or better yet, find a low mileage replacement and do the timing belts/water pump/reseal etc.
February 27, 200917 yr So my car has been running kinda warm lately, like the needle on the gauge goes from the cold to touching the bottom edge of the red as soon as it warms up and then stays there. The time to fix this is the first time it happpens. If the temp is high due to low coolant level, you will need headgaskets sooner or later. I never noticed the oil pressure dropping while overheating. Oil pressure at idle normally drops very low on the gauge. How is the radiator? Are all of the tiny thin fins still stuck in between the horizontal tubes that the coolant flows through? Loose enough of them, and the cooling abaility of the radiator drops. It doesn't take a large percentage to impact this to a noticable amount. They usually rot out where the fan shrouds are first. IF the coolant level is full, a quick test of the thermostat is to remove it. The engine should not get to normal operating temperature.
February 27, 200917 yr Very Respectfully I Want to Add some More information about Engine`s Oil Behaviour. This: when the car overheats you oil will thin out ... is half Right' date=' Let me Explain:[/color'] That only Happens in Monograde Oils. (Single SAE Number Oils) For Example: SAE 30 or SAE 40. Because they have the Same Thickness all the Time, but if Engine`s Temp Raises too High, they Becomes Thinner, sometimes Enough to Change the Oil`s Viscosity, But Thinner Oil ... ... thin out giving you low oil pressure ... ...will Give you Higher Oil Pressure' date=' Not Lower. [/color'] Also, Multigrade Oils, For Example SAE 15W-40 or SAE 20W-50 have Very Different Behaviour: Multigrade Oils have their Viscosity very Thin in Cool Temps, that is the First Number of the two in the SAE Class. (in example: 15W- ...) But While Engine Reaches Higher Temps, the Multigrade oil is Designed to Absorb the Temperature, Swelling and Making the Oil to have Thicker Viscosity Grade, going from the First Number to the Second Number (in example: ...-40) Slowy, with Variation in Thicness depending on Engine`s Temps. Very Different Oil Behaviours. So, if he used Multigrade Oil and Engine`s Temperature Reached too High, the Oil Viscosity went to the Higher Value and Thicker Oil makes Lower Oil Pressure. If the Subie Doesn`t have Oil in the Coolant and / or Viceversa and it was Using Multigrade Engine`s Oil; I Suggest to Fix the Cooling System Problem as Soon as Possible, to Avoid a Head Gasket Damage. Kind Regards.
February 27, 200917 yr That only Happens in Monograde Oils. (Single SAE Number Oils) For Example: SAE 30 or SAE 40. Because they have the Same Thickness all the Time, but if Engine`s Temp Raises too High, they Becomes Thinner, sometimes Enough to Change the Oil`s Viscosity, But Thinner Oil ... ...will Give you Higher Oil Pressure, Not Lower. To a point you are correct - thinner oil is easier to pump, and thus should yeild higher pumping pressure's if all things are equal. What you have not taken into account though is that the efficiency of the pump goes *down* with a thinner pumping medium. The slippage through the pump is higher and so yeilds less pressure and less volume as the oil thins. Also as the oil thins it is pushed out between friction surfaces easier - rod and main bearings leak larger quantities of thinner oil resulting in a higher volume being required to maintain high system pressure. These affects generally cause monograde oil pressure's to drop in systems that employ oil pump designs similar to Subaru's. As they approach operating temperature you are likely to see about 10 psi drop in pressure. GD
February 27, 200917 yr Yes, You`re Right ... ... Also Climates have Something to Do with... For Example I Use Just 20W-50 in my Cars Because I Live in the Tropical Caribbean... So I Wrote about my Experience and Comparison between Monograde and Multigrade Engine Oils in my Country... I Believe that in Cooler Climates, Thinner Oils Shall be Used. I Just Wanted to say that Maybe the Engine`s has nothing wrong with the Oil System, just with the Cooling System and the Lower Oil Pressure could be due to the Higher Temps ... ... Kind Regards.
February 27, 200917 yr I Just Wanted to say that Maybe the Engine`s has nothing wrong with the Oil System, just with the Cooling System and the Lower Oil Pressure could be due to the Higher Temps ... ... Kind Regards. No doubt you are correct in that assertion. The original poster is just not familiar with the tendancy for Subaru oil pressure to read near or at 0 when warm due to the sending unit's being weak with age. And to the original poster - verify all the gauges with proper shop insturments prior to shotgunning parts at the car. Check the oil pressure with a good mechanical gauge and check the temp at the radiator with a laser temp gun. GD
February 27, 200917 yr This is a bit off topic, well actually way off topic, but I just wanted to say that reading GD and Loyale 2.7 Turbo's conversation back and forth is very refreshing. Too bad we can't have more conversations like this on the forum about different topics. I'm very sorry for the interuption. Now back to your regular programming. Patrick
February 28, 200917 yr Author Thanks for the help guys. Now, I remember hearing something about there being "aftermarket" thermostats that don't work correctly/fail prematurely in comparison to the factory Sub units? Am I intarded or am I remembering correctly? Cuz I think I'm going to at least try the thermostat bit because my oil pressure seems to be doing better now for some reason....
February 28, 200917 yr Yes - replace the thermostat with one from the dealer. Aftermarket are inferior in quality. You should double check the accuracy of the dash gauge before you do anything else though. They are not accurate. GD
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