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 Roadside Jerry Your Own Question
Roadside Jerry
Roadside Jerry , Auto Mechanic
Category: Car
Satisfied Customers: 2948
Experience:  Auto Mehanic 39 years,30 with the NYPD Fleet Service Division
Type Your Car Question Here...
Roadside Jerry is online now
A new question is answered every 9 seconds

The lifters seem to pump up and hold the valves open

Customer Question

The lifters seem to pump up and hold the valves open after a short time running. I have details on previous repairs that may be pertenant.
Submitted: 8 years ago.
Category: Car
Expert:  Roadside Jerry replied 8 years ago.
Hello D Criss, The only reasons for the lifters to pump up are, defective lifters, oil pressure that is to high,or the valves were not corrected for the height when the head was rebuilt. When the valve seats and valves are machined,the stem height gets longer, the stem tip is supposed to be ground down by the rebuilder of the head to compensate for this.If the head is resurfaced,it also contributes to the problem. This can cause the lifters to not have enough clearance up give you the problem.If the problem began since the head was done,this is what you will have to look into. Thanks,Jerry.
Customer: replied 8 years ago.
Thank you. I think you have hit the nail on the head. One more thing...How is oil introduced into the lifters and how is excess oil pressure in the lifters relieved?
Expert:  Roadside Jerry replied 8 years ago.
Hi, I am going to send some info on lifters for you. Oil is feed under presure to the lifters throuh oil supply holes in the bore the ride in.When the cam comes up to the high spot the lifter check vlave closes,and the oil is trapped inside,making it allow the valve to open. When the valve is open the check valve in the lifter is supposes to open and release some oil. That is why you need the slight play in the valve train,if to tight the pressure cant be releases and the lifters pump up.

A hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. The Conventional means of adjusting valve actuation always require a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear. The hydraulic lifter was designed to ensure that the valve train always operates with zero clearance, leading to quieter operation and eliminating the need for periodic adjustment of valve clearance.

The hydraulic lifter consists of a hollow expanding piston situated between the camshaft and valve. It is operated either by a rocker mechanism, or in the case of one or more overhead camshafts , directly by the camshaft. The lifter is filled with engine oil intermittently from an oil galley via a small drilling. When the engine valve is closed, the lifter is free to fill with oil. When the valve is opening and the lifter is being operated by the camshaft, the oil feed is blocked and the lifter acts just as a solid one would, oil being incompressible.

[edit] History

The first firm to include hydraulic lifters in its design was Pierce-Arrow in the early 1930s. Hydraulic lifters were popular on automobiles designed in the 1980s, but most newer cars have reverted to bucket-and-shim mechanical lifters. Although these do not run as quietly and are not maintenance-free, they are cheaper and rarely need adjustment because the wear caused by operation is spread over a large area.[citation needed]

[edit] Disadvantages

There are a number of potential problems with hydraulic lifters. Frequently, the valvetrain will rattle loudly on startup due to oil draining from the lifters when the vehicle is parked. This is not considered significant provided the noise disappears within a couple of minutes, typically it usually only lasts a second or two. A rattle that does not go away can indicate a blocked oil feed or that one or more of the lifters has collapsed due to wear and is no longer opening its valve fully. The affected lifter should be replaced in the latter circumstances. In extremely rare circumstances, a lifter can "pump up" and create negative valve clearance so that its valve cannot close. This is more serious as burnt valves will result. In all cases it is important to follow the manufacturer's recommendations for oil viscosity and quI amality

Roadside Jerry, Auto Mechanic
Category: Car
Satisfied Customers: 2948
Experience: Auto Mehanic 39 years,30 with the NYPD Fleet Service Division
Roadside Jerry and 6 other Car Specialists are ready to help you
Customer: replied 8 years ago.
This is most interesting. Thank you. I have determined that the rocker screws have 20 threads per inch. A 1/4 turn will result in 0.0125 inch
lateral movement. I can losen the rocker screws one quarter turn AND THE ENGINEE RUNS FINE. I will have to return the head to the machine shop that did the work or maybe use two head gaskets. What do you think?
Expert:  Roadside Jerry replied 8 years ago.

Hi,I am glad to hear you found the problem. As far as the fix,the correct way would be to have the heads returned to the machine shop so the valves stem tips could be ground down that amount. I would believe that if you had available a small grinder and were able to keep any debris out of the engine it could possibly be done with the head still on the engine in the vehicle.I also might be tempted to clean the rocker screws and threads throughly and use loc tite on the threads and leave the adjustment set so it runs,or try to shim the rocker adjustment up, if possible. As far as 2 head gaskets,I found a company the makes head gasket shims of various thicknesses,it would be safer then using 2 gaskets I will send you a link,and a copy of a page from the site. Thanks for the accept,good luck,let me know how it works out for you,Jerry.


JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Previous | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, do indeed know your stuff. Jim Castleberry, FL
  • Excellent reply, and also very quick. Really sounds like the Expert knows what he is talking about. I will be back to use your service when I need more help with my RV. Dutch USA

Meet The Experts:

  • Chris (aka-Moose)

    Chris (aka-Moose)


    Satisfied Customers:

    16 years of experience
< Last | Next >
  • Chris (aka-Moose)'s Avatar

    Chris (aka-Moose)


    Satisfied Customers:

    16 years of experience
  • Ted G.'s Avatar

    Ted G.

    ASE Certified Technician

    Satisfied Customers:

    20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
  • George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    ASE Master Tech 15+ yrs, AAS Automotive Technology, Factory trained Asian specialist
  • GM Tech (Cam)'s Avatar

    GM Tech (Cam)

    Auto Service Tech

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
  • Amedee's Avatar


    Former ASE Master Tech

    Satisfied Customers:

    ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
  • Jerry's Avatar


    Master Mechanic

    Satisfied Customers:

    ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
  • Richard's Avatar


    ASE Certified Technician

    Satisfied Customers:

    12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes