I recently bought a 91 RS, I find it to be nice and strong while its cold but when it heats up it loses all its power. I took the valve covers off last night and found some milky gunk under it, indicating to me it had coolant in the oil. I assumed it to be a head gasket but I wanted to be sure before I took on all that work. I read around and saw others with similar problems and people believed it to be their intake gasket, obviously that would be a much easier solution if it was. Either way I will be taking the intake off so I can check that, but does this sound more like a head gasket than an intake gasket? I'm leaning that way but I was curious about others opinions. Thanks for the help!

 

From what you said: "I find it to be nice and strong while its cold but when it heats up it loses all its power", that's a classic intake gasket leak/warping manifold symptom. With coolant in the oil added to the equation, a head gasket is another possibility, but it still could easily be the intake. Since the intake manifold has to come off before the heads do anyway, you should be able to see a sign at the gasket if that is the leaker.

 

pull the dipstick and see if it is mixed. if it is not then remove the tbi and clean the passages underneath to allow the pcv system to work correctly. if you are only seeing a white oily build up on the bottom of the valve covers this will fix it. also reseal the intake. they are known for leaking at the back cylinders.

 

if it is only on the valve covers and not in the oil, that would more than likely be condensation. wasting a year of my life changing oil, i would sometimes see an inch thick yellowish goop on oil caps. it wouldnt hurt to change the intake gasket as well as previously stated

 

If coolant in the oil is suspected, you should allow the car to set overnight. Then in the morning, momentarily pull the drain plug from the oil pan and see what comes out. Since oil floats on water, any coolant (if you have any) will be at the bottom of the oil pan. Also, if you suspect coolant in the oil, you would want to do this before running the engine again as the oil pump sucks off the bottom of the pan. Engine bearings are kinda fussy, they prefer oil over coolant as a lubricant.

 

I appreciate it guys, I hope that it is just the intake gaskets, much less time consuming to fix. I intend on putting a 350 I'm building in this summer and I want this 305 to last me til then. Does anyone know exactly what it is that would cause it to lose power with this leak? My buddy was asking and I didn't know. Again thanks a lot!

 

What he said. Very common issue with the 305's If you oil is clean, not milky its most likely PVC system. It is also common on cars that only get short trips. They never reach full temp and the moisture collects in the top of the valve covers. I can not remember coolant ever leaving a white film it always a milkshake color.

 

When cool, your intake manifold is nice and sealed....when it warms up, it expands and exposes any leaks you have, causing vacuum leaks and wreaking havok on your system. These can be tough to trace....

OR, your choke is improperly adjusted....

If you had a head gasket leak, you would also be experiencing other symptoms....coolant gauge constantly swinging up and down, puffy exhaust, brown milky oil....

I also suspect just plain old condensation in your valve covers.

Check your carb/throttle body for proper choke.....then maybe look at an intake leak.