amc 258 with howell TBI blows oil

[Guest]

So my 258 is showing little to no oil psi. 20psi crusing on the highway, sometimes its at 40 on startup. Brand new pcv valve, i KNOW the filler cap isnt very tight, brand new vc and rubber vc gasket permatexed as well. It had a breather on the rear port hole. Im stumped ive tried everything there is to try. Anyone have any ideas to fix the oil blow by?

[heap o' jeep]

Sounds like there is excessive engine wear, my old 200k+ 4.0 used to have the same symptoms. I substituted a quart of oil for Lucas Oil Stabilizer and used Rotella 15w-40 oil. Definitely helped out with oil pressure, It wouldn't dip down to around 0 anymore when the engine was warm on the trails. Not a "fix", but a good band-aid for sure

[Guest]

Yeah this 258 is all original except for the TBI kit. It only has 135k on the clock right now. Replaced the VC and the gaskets twice and it hasnt seemed to help one bit. Il retorque the bolts, i fabbed up a new grommet addition out of foam to put underthe rubber one on the filler cap and il see of that helps any.

[Guest]

Well it held good oil pressure for about 20 minutes now its back to blowing oil out the cap again. Opened it up and it was smoking hot in there.. Im stumped.

[Red Betty]

i would do a compression test and a leak down test. whats the water temp at? whats probably happening is your rings are shot which is letting that compression leak by. this causes air to be going from the bottom of the motor up through the engine and out the breather. with the air doing that its not allowing the oil to drain to the crank case properly and it gets pushed out the breather. if you put a really thick oil in it that will help but like he said its not a fix. it could have also broke a ring i would say its probably time for a new motor.

[Red Betty]

low oil presure could have been to blame. if it didn't have enough pressure to lube the cylinders it could have killed the rings.

[Guest]

I have 2 spare 258s one complete one missing a vc and carb. The jeep dont smoke out the exhaust only on a startup then its nothing. Im thinking along the lines of the oil returns are clogged. Its keeping all the oil up at the top and pushing it out the filler. I could be wrong and red betty could be right. By the way Red Betty im the guy who bumped your for sale ad on kcsr. milanogsr. lol

[Red Betty]

oh well thanks again for the bump. like i said i would start by doing a compression test and a leak down test they will tell you a lot. how bad does it smoke on start up? if it is the oil returns clogged it realistically needs to be rebuilt. you can try to clean them out but you have to do a really good job or you'll have all that hard burnt oil floating around your engine and that can take out a bearing. i would start looking at those other two motors you have and pick the best one.

[spunebil]

I have same deal with trucks engine and I figure 1 its not enough pvc flow or 2 its compression blowing past rings ( which I dont think it is) as it has new rings/hone cylinders , etc. ;)

I still think its pvc related :)

Especially since I dont burn oil ( at least no smoke! ) :)

[Guest]

Yeah i just dont know. The jeep runs great. Its a little hesitant on cold start ups and taking off before it gets warm. Feels like it wants to die and what not. Once its warm though its no problems besides the oil psi

[Guest]

oh well thanks again for the bump. like i said i would start by doing a compression test and a leak down test they will tell you a lot. how bad does it smoke on start up? if it is the oil returns clogged it realistically needs to be rebuilt. you can try to clean them out but you have to do a really good job or you'll have all that hard burnt oil floating around your engine and that can take out a bearing. i would start looking at those other two motors you have and pick the best one.

Yeah i hear that man. I was hoping it wouldnt come down to that. Im an optimist haha but i think im gonna go with a different 258 with a carb this time and sell the howell TBI kit since its basically brand new.. 7 months old.

[Red Betty]

i would keep the injection especially if you go wheeling with it.

[Guest]

Yeah who knows man. im up in tue air everyday. first its a 4.0 head swap 304 swap. i just dont know man

[Guest]

So i figured id take a look at the cam bearings and mains this weekend since it will be a bit warmer. Il throw in my janky 360 and get next to no gas mileage for a week til i get this **** figured out.

[spunebil]

Just read me earlier reply, I have oil blow - by but oil pressure never drops ;)