black tar in lifter valley??? All: I pulled the intake off my 350 and found black gruck running down from the head to the lifter valley. It was similar to aerated grease or tar. I looked closely at the head gaskets and they did not appear blown. The last time I saw this was after the oil pump failed in a sb Dodge. Has overheating caused a problem some time during this engine's life? If not, what could this be indicative of. TIA
down the center? was it down the center of the lifter valley? it could just be from the excess heat of the heat cross over. thru the center hitting some of the oil thru there.. could also mean a leak at the heat cross over as well. check the intake for cracks. Nate
oh Thanks for the reply Nate. The "flow" starts at the head gasket and ends at the lifter valley. Can you elaborate on your heat cross over theory? I'm pretty green.
what part? what part of the head though? full length? or just the middle? the heat cross over is the center most port of the intake manifold goes under the carb thru the intake into the other head. these are the ports that are the cross over. Mine had a crack at the green spot before I put it on. so it maybe kinda common. this cross over is generally for the heater of the choke coil that sits in the head. other than that I'm not sure what it is. a crack there could cause hot exaust gas to enter under the intake and possably burn some oil quickly.
middle-ish? Nate: The deposits were aft of the center of the head, midway between middle and back. I imagine your diagnosis is correct. Is the source of warm air for the cross-over the crank case? If so, would a leak encourage oil to be forced up through the block and into the lifter valley through the head gasket? Or is the leak simply super-heating the oil directly adjacent to the leak? Sorry to be Mr. Question but I am anxious to learn. I've been looking forward to this since for a LONG time.p Thanks again!:TU:
Re: middle-ish? wish i could see it. Now I'm not to certan with my theory.. what did the mating surfaces of the intake gasket look like? no the source of warm air for the cross over is exaust gasses thru that center port (if you look in the center port you can see 2 holes about 1/2 in dia. I believe that these are looking at the exaust valves. thru the head. so if there was a leak you would have exaust gas going into the crankcase. but now you say its a lil further back. and I'm not sure where it would be from. unless it is super heating the oil. and somehow flowing back. or a small crack in the intake/head area. like at one of the corners. I had sludge built up on the underside of my intake on the PCV valve end. if its simmilar to that then I'm not to sure why just this one spot has it. Nate
now.. if all that oil is only one one piston. makes me wonder if you have a shot ring creating some extra heat there.... but in theory it should also be on the oil pan side as well. something to try is to see if you can bottom out that cylinder (turn the engine over till that piston is all the way down and just look at the skirt of that piston. if it is obviously discolored it got a lil warm. some burnt oil on it I think is pretty normal for a high milage engine. I'm asuming your doing the work with the engine in the car. Nate
hmm.... hmm.. maybe it was just a bad gasket. or just the previous owner didn't change the oil :af: other than that i'm not sure what else causes that. keep us posted Nate
