How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jeep Service Your Own Question
Jeep Service
Jeep Service, Jeep Owner
Category: Jeep
Satisfied Customers: 4750
Experience:  14 years with AMC/Jeep Specializing with pre-1994 Jeep products.
14892859
Type Your Jeep Question Here...
Jeep Service is online now
A new question is answered every 9 seconds

Just did a cam and lifter swap on a jeep 258 and have

Customer Question

Just did a cam and lifter swap on a jeep 258 and have excessive blue smoke after about 20-30 seconds of start up. It smokes at idle, acceleration, and when you release the gas pedal. It did not smoke before the swap. I did the 30 min break in procedure running it between 2,000 and 2,500 rpm with breakin oil. Compression checked good at 150 psi per cylinder, and a leak down while engine was cold tested between 15% and 20% loss per cylinder. To be sure the valves were closed since I had the valve cover off, I released the rocker arms.
This was a rebuilt engine that I have put approx 30,000 miles on it. I did notice that there were two sizes of pushrods, with no rhyme or reason (intake or exhaust). Also one of the new lifters will allow the pushrod to be pushed down approx 1 mm, when I thought the lifters should pump up tight with oil. I think this has allowed the rocker arm to feel loose, which I think may be the cause of some valve train noise. The sound is not coming from deep where the lifters are, but higher where the rocker arms are.
My two concerns are the blue smoke, and excessive valve train noise. Any help would be appreciated. Thx.
Submitted: 1 year ago.
Category: Jeep
Expert:  Jeep Service replied 1 year ago.

Hello. Welcome to Just Answer. Please allow me to assist you.

Expert:  Jeep Service replied 1 year ago.

Whilst not knowing what cam and lifters (specific heights, not just the part number), this sounds like you have a couple different things going on here. First, changing the cam should never cause you to have blue oil smoke. The 258s are notorious for blow by. Let's do this first: Start it up, and pull off the PCV hoses form the valve cover. Do you see smoke/vapor, anything being chugged out of the open valve cover holes?

The valve train issue is most likely worn rockers and pivots. If you put a higher step cam (even a little bit higher), this stresses the rockers and pivots. You would do well to replace all of them. This too would not cause blue oil smoke. It is common for these engines to lose an oil control ring due to breakage (you would never see this on a compression test), or, the oil control rings are carbon seized. This is VERY common, as the combustion chamber , intake manifold and carb are very poorly designed. This allows carbon buildup in all kinds of places....in the intake, on top of the intake valves, and in the oil control rings. This really sounds like you are going to need to pull the pistons out.

Expert:  Jeep Service replied 1 year ago.

It would also be my thinking that the break in oil combined with some carbon buildup on the oil rings caused them to seize up.

Expert:  Jeep Service replied 1 year ago.

If you have any questions, please feel free to reply; I will be very glad to help you further.

If you do not have any questions, and are satisfied with my input on your request, thanks for choosing Just Answer. It was a pleasure to assist you today. I trust my input to your request is satisfactory to you and meets your expectations.

A positive rating would be greatly appreciated for my assistance on your inquiry.

Thanks in advance and thank you again for choosing Just Answer

Customer: replied 1 year ago.
Comp cam kit k68-231-4. (gross lift-.462 intake, 485 ex, Duration 250/258, Separation 111).Just got off the phone with comp cams and they agreed the lifter is bad, and they are sending me another. I agree with replacing the rockers and pivots, but if the lifter us not fully loading with oil and leaves the rocker loose when not under load, I would think that would create addition mouse, yes?Remember, before the cam swap, no blue smoke. Immediately after the swap, smoke. Do the oil rings all go at once or is it usually gradual? Also, you never mentioned valve seals. I have noticed these seals get pushed to the top of the lifter and don't want to stay down over the guides (umbrella seals). These lifter springs have a damper (flat spring inside the main spring) which looks like it catches the seal and holds it up.I run weber 38, Clifford intake, 6 into 1 hedman exhaust, MSD ignition, and no problems with blue smoke before. Also run breathers and no PCV to keep the notorious blow from recirculating. Not a lot, but yes, always had some.It would be a shame to tear it down to the pistons to find out it wad something simple like valve seals or cam timing. Please give it more thought. Thx
Expert:  Jeep Service replied 1 year ago.

Cam timing, no. Valve seals? Absolutely. If they are lifting, you are getting oil sucked down the intake valve stems. That would explain the instant blue smoke. I'd rethink the valve seals before anything else. Good point and call on that.

Customer: replied 1 year ago.
are the valve seals (umbrella seals) supposed to lift up and stay attached to the valve stems as they rise up and go down? If not, how do you keep them from lifting?
Expert:  Jeep Service replied 1 year ago.

I'm pretty sure that umbrellas need to attach to the valve guide and stay put. They should not move. Either you have the wrong umbrellas or you need to machine the valve guide to accept and hold the seals in place. If the seals are being lifted up as the valve stem closes (raises), oil is being drawn down the valve guide. If you have a lot of blue smoke, you probably have worn valve guides too. If this engine was in my shop I would eb replacing the valve guides and machining them to hold the seals tight

Expert:  Jeep Service replied 1 year ago.

If you have any questions, please feel free to reply; I will be very glad to help you further.

If you do not have any questions, and are satisfied with my input on your request, thanks for choosing Just Answer. It was a pleasure to assist you today. I trust my input to your request is satisfactory to you and meets your expectations.

A positive rating would be greatly appreciated for my assistance on your inquiry.

Thanks in advance and thank you again for choosing Just Answer