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Land Rover Repair/disco series 2 v8 engine knock

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Expert: John Elder Robison - 7/12/2009


Question
QUESTION: John i have a knocking sound coming from cylinder 7 .i found that by disconnecting the plug the noise stops.i pulled the sump off and visually inspected the big end bearing and it looks ok.i have plastigauge what is the max clearance allowed?
what else can it be?Can i replace only one bearing if needed.by the way it is not a loose liner as i had them all replaced by tophat liners a couple of years ago.


ANSWER: The knock is more likely to be a loose piston.  The rod clearance has to be low, 1-2 thousandths but that is never the problem unless the berings is actually melted.

The skirts collapse by 5-10 thousandths and then the pistons rattle.  I have seen that several times before

---------- FOLLOW-UP ----------

QUESTION: John,Can i re-use the head bolts more than once?
Can the head be removed without taking the motor out,the last bolt seams hard to get to.'against the firewall'
can the bolts be replaced with ones that can be torqued by wrench rather than torqued and then 90 degrees?

Thanks for your help Rob.

Answer
The head bolts tend to snap if you try and re-use them.  I advise against that from personal experience.  The heads certainly come off with the engine in the vehicle.  I know one bolt is in the corner back there but we use an allen socket and 1/2 inch drive breaker bar adn take it right off.  The "torque to yield" bolts have replaced "torque to a number" on most high performance engines. LR is not alone in using them.

Good luck with it,
John

Check my car blog at http://robisonservice.blogspot.com  My regular blog is http://jerobison.blogspot.com and I'm also on Facebook and @johnrobison on Twitter

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John Elder Robison

Expertise

I own J E Robison Service in Springfield, MA. We are Bosch Car Service for Land Rover, BMW, Mercedes, and other European lines. I can answer most questions about Land Rover service or repair. I'm known as a car enthusiast, machine aficianado, photographer, writer, and speaker. I've been around Land Rovers and British cars most of my life. Visit me at my car business, www.robisonservice.com or my author website, www.johnrobison.com. Check out my autism and writing blog at jerobison.blogspot.com or my photos on www.pbase.com/robisonphoto John Elder Robison

Experience

I have been a Land Rover service manager since Land Rover returned to North America in 1987. My company is a four-star Bosch Car Service facility, known nationwide for Land Rover service, overhaul, customization, and restoration. We're a dealer and service agent for APCO, backer of the Land Rover Assured and Certified dealer service contracts and Easycare independent service contracts. In addition to Land Rover our company services BMW, Jaguar, Mercedes-Benz, Rolls_Royce, and Bentley motorcars. We have factory-plus-level service capability for all makes. Visit my company online at www.robisonservice.com > service > land rover Also visit my blog at robisonservice.blogspot.com

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ASA IATN NPPA PPA

Publications
In the Land Rover world, my writing can be found in Land Rover Lifestyle, Land Rover Monthly, The Rover News, The Rover Log, The Rover Reference. In the wider publishing world, my work is published by 20 publishers in over 50 countries. Look Me in the Eye is a New York Times bestseller and an international bestseller.

Education/Credentials
I am ASE certified, Bosch Trained, and trained by Omnitec/T4 and Autologic on their Land Rover test systems.

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