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What is all over my intake


scrapper

Well-Known Member
U.S. Military - Veteran
Joined
Nov 27, 2008
Messages
513
City
central IL
State - Country
IL - USA
Vehicle Year
1994
Drive
2WD
Engine
302
Transmission
Automatic
Total Lift
6+3
Tire Size
33/12.50/15
I am replacing intake gaskets and found
036.jpg

038.jpg

Looks kinda like oil burnt to the inside. What is that from? Would this be something wrong?
 
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100% normal. It's gas. Every time you shut the engine off there is a fuel injector that had just fired. If the engine stops before the intake valve closes completely the fuel goes back through the intake as it evaporates. That gunk is what gets left behind as it "boils"off.

Whenever a shop tries to sell you an induction cleaning service that is what they are going after. That little bit isn't an issue, but it can build up on the back of the intake valves and cause problems. It can also build up much thicker than that and cause problems.
 
I was hoping it would be something broken, fix this and the bad miss would go away.lol I will finish up the injectors and clean everything. I really think there is a problem in the last cylinder. I will find out in a bit.
 
Well I got the intake off. I have a couple of photos can anyone tell me if the one is a hole for a distributor. My truck is a 94 and I thought they didn't have one. I am not sure what else it could be. There are a couple of sensors in the back one in the block and one in the head, what are they for? Why is there a hole in the head blocked off by the intake gasket that has water in it? I cant find my chiltons book right now. Thanks for any help.
001.jpg

I think this is a hole for a distributor?
005.jpg

This is the 2 sensors
003.jpg

not sure what this is but the hose has the pcv valve in it.
 
In the last picture, the rounded 'can' at the bottom is the oil separator, which should have the PCV valve stuck into the hose leading from it. The distributor would be in front of the separator, just rearward and below the alternator.(if the alternator is drivers side mounted)
You do not have one with the 8-plug setup, but instead have two coils, one for each side of the cylinder head.
In the second picture, there is shown the sending unit for the oil pressure gauge, just rearward of the last intake port, protruding from the side of the head. Almost directly below, covered in oil and schmutz is the temperature gauge sending unit. There should be a wire stuffed onto the threads on the end of the sending unit that connects to the gauge or light. Disconnected, I bet the gauge doesn't work.
There is/was a connection from the cooling system to the intake manifold that circulated coolant to heat up the manifold for better evaporation of the fuel, allowing it to run better when cold using less fuel(I think). When EFI was installed, back in 85, the cooling system was still plumbed into the bottom of the intake manifold, so you likely have a 'stub' of coolant that just sits, unless you have the small hose routed around the back end of the head from one of the heater hoses.
tom
 
There are wires on the bottom one they just blend in. The top photo has a bump out with a big nut and a bolt above it. I was hoping that was the hole for a distributor. lol just hoping. I really want to put a carb and a distributor on it.
 
Its running better no miss but wont stay running, idle sucks. I cleaned all the crap out of everything, it was everywhere. Thick and sticky.
 
I just found out that number 4 cylinder is about 50 on the compression test and 3 was about 75. I am going to pull the head and give it a look. I took the valve cover off and the head looks like this
012.jpg

011.jpg

Is it possible that the head gasket is bad, or the valves not sealing? or is it more likely the bottom end?
 
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Many, but not all, situations where adjacent cylinders both have low compression are created by bad head gaskets allowing leakage between the cylinders.
I do not know of a test to guarantee that, but suppose if you removed the spark plugs, and were able to provide air pressure to one cylinder with both of its valves closes, and heard of felt the pressurized air coming out the spark plug hole of the other cylinder, it would be pretty definitive.
Do you have excessive pressure in the cooling system? Bubbles of air(exhaust gas) coming out the radiator filler neck? That is another symptom of a blown head gasket.
tom
 
I took the valve cover off and am pulling the head in a bit. I dont know but does the wear on the cam look ok? I turned it by hand and did not notice anything odd, wear surfaces on the cam were smooth, lots of small crud parts around but not bad.If the cylinders are smooth and pistons look good could it be a cracked head? I'm wondering what to look for. I will check the block and head to see if its warped, I heard something making noise and was sure it was coming from the head area like a rattle, but only once in awhile. The valve springs seemed to compress and un-compress as I turned it. Guess I will be back in a bit. With a couple of photos
 
I pulled the head and have photos. I closed the valves on both 4 and 3 cylinders and sprayed carb cleaner until it was above the valves, and in both both cylinders the exhaust valves had carb cleaner running out of them. The intake valves were sealing good enough it evaporated no wet under the valves. I'm wondering if the head could be cracked or does it seem like it just needs a valve job? I looked it over and did not see any cracks but I know you cant see most of them. I know these heads seem to crack a lot. It looks like the last 2 cylinders had a lot of crap all over.
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003_1.jpg


004.jpg


001_2.jpg


Do the photos help any ideas?Messed up had to take off all the crap I just put on. :annoyed:
I was so going to pull the head but thought the other stuff would solve the problem. Mad at me...
 
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I think I'd remove the exhaust valves and take a look at the seats. Likely are pitted and worn. Depending on condition, you may want to take the head to a machine shop and have them do some work on the valves & seats. You may need some new valves.
If it will not hold liquid, it will definitely not hold gas(fuel:air mix).
You might want to take a look at the hydraulic valve lifters(supports) as they can cause the valve to stay off the seat a bit and allow it to get too hot, which will make it leak eventually.
There may be some stuff in the cooling system that is preventing the head from absorbing and transferring the heat from the exhaust valve seats to the coolant. Check for sludge in the water jacket, or blockage of any kind.
Keep stuff out of the rearmost hole in the block, next to the last head bolt. That is the oil flow passage from the pump to the head. The oil travels across the head, and up around the next head bolt forward from the rear. You want that clean.
tom
 
I'm going to take it in to get the head checked and a valve job. Would the valves leaking like that keep the compression down to 50 and 75? I was just a bit worried about the bottom end. I just need it to keep running about 6 months. I think rebuilding the whole engine is a bit to much money right now.
 
Leaking valves will cause compression to read a lot lower. As the rpms increase, they will effectively start to seal better as there is less time for leakage past the seat.
I have seen( wanna pic?) valves with pie-cut shaped wear, and with slices missing that have zero compression.
If you are lucky, the valves can be ground, the seats cleaned up, and it will work better. Check the supports/lifters for those cylinders for sure. Make sure you can compress the lifter as a frozen lifter will (can) keep the valve from seating and it will cook again in no time.(well... some time) If you cannot compress the lifters, take them out, and disassemble & clean. Re-assemble using the same parts(do not mix!!! !!! !!!) and put back into the same place they came from. Check also that the valve springs have some strength, as springs that have gotten hot may lose their temper, and be weak. Weak valves will not seat tightly, and cook as above, and may not work well at higher rpms.
Something caused these to burn. If the cooling system has been neglected, now is a good time to remove the pump, and flush from the rear coolant passage holes in the top of the block. Any sludge and stuff will have an egress port through the pump hole.
IF you do that, make sure to dry the cylinder walls after. You will likely be unable to keep water/coolant from getting into the cylinders atop the pistons. You can use rags or paper towels to sop up the coolant, and then rotate the engine slowly, by hand and examine the cylinder walls for droplets, wipe, repeat until you don't get any drops after rotation. You can also use a rag/paper towel wetted with engine oil to wipe the cylinder walls and prevent flash rustification.(rust)
tom
 
I think the injectors were clogged and it ran lean.I replaced them and It would run great at 65 but idle was really low. I am thinking that may have been the problem? The guy at the machine shop gave a once over to the head and said he didn't see anything obvious. I will find out soon. I hope its just the head. With a gasket set and head bolts, I'm going to guess about 300.00 or so... Tired of riding to work with the wife, she is bitching about having to go in an hour early. I don't blame her just don't want to hear it.
 

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