budz1065

some questions for you motor heads. My 86 302 FI F150 is giving me grief. My low budget leaves me with getting parts and putting them on when I get time. The truck is not my primary trans but I would like it to be when it is more reliable. Prob is this. When the truck warms the oil pressure drops. If I dont rev it up and restore the pressure the motor hiccups and starves for power. Also, when the motor idles too long with the absent oil pressure it stalls, overheats (I did put in a new thermostat?) and wont restart till it cools. The motor also has an exhasut manifold crack that opens more when it is hot, would this drop my compression and or oil pressure? I have changed the oil and used Lucas. I also put some Seafoam in the crankcase (1000 miles after oil change) I am thinking I need a oil pump. I just need to know what else besides the pump and drveshaft I need for the job, like an oil pan gasket and pump mounting gasket? Should I even bother? IS this moter gonna ****? Am I misdiagnosing this? It only has 160,000 on it but it sat for a while. Thanks in advance.

budz1065

bump????????????

Bill Z

Quote:

Originally Posted by budz1065

some questions for you motor heads. My 86 302 FI F150 is giving me grief. My low budget leaves me with getting parts and putting them on when I get time. The truck is not my primary trans but I would like it to be when it is more reliable. Prob is this. When the truck warms the oil pressure drops. If I dont rev it up and restore the pressure the motor hiccups and starves for power. Also, when the motor idles too long with the absent oil pressure it stalls, overheats (I did put in a new thermostat?) and wont restart till it cools. The motor also has an exhasut manifold crack that opens more when it is hot, would this drop my compression and or oil pressure? I have changed the oil and used Lucas. I also put some Seafoam in the crankcase (1000 miles after oil change) I am thinking I need a oil pump. I just need to know what else besides the pump and drveshaft I need for the job, like an oil pan gasket and pump mounting gasket? Should I even bother? IS this moter gonna ****? Am I misdiagnosing this? It only has 160,000 on it but it sat for a while. Thanks in advance.

My suggestion is to remove the radiator cap and drive a new truck under it.

Seriously; it sounds like the 160 miles your truck has had were hard miles. Many start and stop sort of miles. Eventually (maybe sooner), you will have to have the engine rebuilt. When it heats up, everything expands a little. That is one reason why the oil pressure drops. I also bet you are having a carburetor issue which shows up when the engine is hot. If it hasn’t been replaced before, your timing chain will have stretched and will need to be replaced.

Short term: Since it is summer, try using the oil at Wal-Mart labeled for older car and trucks. This oil comes heaver weight and thicker than the other. This may keep your pressure up. You will have to change the oil more frequent.

If you want to replace the oil pump, you will need a pan gasket and the pump. I don’t think your 86 requires a pump gasket but ask the parts store guy. Your old pump drive shaft should be OK. There isn’t much to ware on them. The hard part is raising your engine high enough to get the pan off. When you get your pan off, check for metal and junk in your pan. I bet you have a bunch.

With that age of engine you should schedule an engine change or rebuild. If you do have the engine rebuilt, go with a brand new oil pump then too. Don’t think that because you changed the pump out now that you can use the same pump on a later rebuild. Not good thinking. Another thing, think about just replacing your motor with one that you can hear running good. May be cheaper than a rebuild.

A cracked manifold would not change your compression but it does irritate people near by plus the carbon monoxide may kill you. Have that manifold repaired or replaced. Manifolds can be welded. Must be done by some one that KNOWS how to do it. Maybe cheaper to just get one from a salvage yard.

Hope some of this helps.

NGM

The older 302's had a plastic coating on the timing gears. Pull the oil pan and see if its full of crap. If it is then ya need to do a timing chain and gears also. What happens is all that crap falls into the pan then gets sucked up against the iol pump pickup. The really small stuff wears on the oil pump gears. So its a good idea to do the pump at the same time.

Attach a manual gauge to the truck to see if its really losing pressure or if its a bad sender.

spl152db

what years did they put plastic parts on the timing chain? i just bought a used 1990 motor and found little pieces of plastic in the oil pan, but i also found them under one valve cover. im thinking it was an old oil cap that broke apart, but can never be for sure. i tore the motor apart and no apparent damage has occured.

mine has a double roller.... is that stock?