Questions and Answers

Infiniti Q45 Hydraulic Valve Lifters Q. Hello, I have a 1997 Infiniti Q45. This car has a DOHC 32 Valve 4.1 liter V-8 engine in it. It also has 61,000 miles, manual transmission, fuel injection, ABS Brakes, A/C and cruise control. Unfortunately I've been the victim of an engine tick that comes and goes in a somewhat inconsistent fashion.

I've been told by the Infiniti service shop that it is a bad engine lifter that needs to be replaced and that they would replace all of them because if one is bad than the odds of another going bad is high and that it's hard to pinpoint which lifter is causing the noise.

The car only has 60,000 miles on it and it's pretty costly to repair the lifters so I'm at a loss and I'm trying to better understand what exactly is going on. I know for a fact that if I drive the car for an extended trip of 80 to 100 miles that it will start ticking. It also seems to stop ticking out of nowhere.

Sometimes after it sits for a few days, sometimes after I park the car on a 30° incline with the front end up and sometimes it just stops ticking while I'm driving it around town. I understand how a DOHC engine works so I'm curious as to the roll of the "lifter" in this process. Is the lifter the spring that is connected to the rocker arm?

Also, these are hydraulic lifters, so how do they work and is that why it is so expensive to replace them? Also, I was told that there is a very small hole that oil flows through so the lifter can fill up and down with oil so the engine can adjust as it gets hot.

Since the lifter tick comes and goes does that mean maybe the hole gets plugged up and unplugged? Maybe when I park it up at an angle somehow the lifter fills up with oil again? Another Infiniti service shop has suggested an engine treatment where they drain the oil and flush the whole engine with high pressure, hot water and that can sometimes clean out the lifter holes that may be plugged with debris.

This costs $150.00. Would this be worth it? Or do I most likely have to replace the lifters and just pay the several thousand dollars to do it?

Thanks for your assistance and any information you may have.
Sincerely,
RJ

A. First off RJ, if you like your car then do not ever get an engine flush. An engine flush is like playing Russian Roulette. One day you'll pull the trigger and you will be picking up the pieces of the engine you left behind.

I have used a method of cleaning the lifters that is much less radical and works about 75% of the time. Get an oil and filter change and substitute one quart of ATF for one quart of oil. Run it for about 3,000 miles and do it up to three times. If they still make noise, then they probably will need to be replaced.

The lifters, or Hydraulic Lash Adjuster, (HLA) automatically take up any play in the valve train. Pressurized oil is fed into the HLA which pumps it up. Then there is a check valve that prevents the oil from coming out maintaining 0 valve clearance.

When the engine is cold and there is more clearance in the valve train, the HLAs pump up and it is not unusual to rear a slight tap for a couple of seconds with a cold engine. When dirt or sludge gets into the HLA and it's check valve, it can no longer hold oil and thus you get a noise.

I really don't think the angle the car is parked would have any effect on the HLAs. But who knows? They said I would never find a girl stupid enough to marry me and I did.

Since the HLAs sit way down in the engine it is labor intensive to replace them. And since you have 32 of them to replace, parts cost will be high.