CMV991

Hope I'm doing this correctly! I bought a '95 LS400 w/130K 18 months ago from 2nd owner. Have all maintenance records since day one. Currently at 170K+ w/o any issues.

Problem: After start up and hitting the road, before engine has warmed up....on acceleration, there's a less-subtle-every-day engine knock. Used to completely resolve after warmed up, but now is still there.....just less pronounced. No noticeable loss of power, and still runs like a top, but has become noticeable enough that action needs to be taken.

Based on past vehicles with which I'm familiar ('69-72 Datsun 240Zs and 510s), it sounds like timing is off, crack in manifold, etc.
One thing of note: Bought car in Ft. Meyers, FL. When completely warmed up, temp gauge barely reaches 2nd mark (I believe). Way south of midpoint between cold and hot. Always wondered if thermostat was changed to accommodate S. FL heat.

I've continued to use the synthetic Mobil 1 previous owner used.
Any predictions, insight, feedback, etc. would be much appreciated before I attempt to find an honest, competent shop in my area, near Gainesville, FL.

Thanks & all the best, -Chuck

Rdrcr

Knocking or clicking?

I originally thought I had either a knock or an exhaust leak on my '94 but, after taking my mechanic for a ride, it was diagnosed as noisy injectors. According to my mechanic it is pretty common with the 1UZ-FE.

Mike

AandSC

Get a mechanic's stethoscope and see if you can pinpoint where the knock is coming from.

dicer

It could also be valve lash. These do not have hydraulic lifters or what ever you wish to call them.
I hear valve lash that is always much louder than an injector is.

brybo86

When the temp is at the second mark how warm is the heat when set to HOT?
What does a scan tool say the engine temp is when on 2ND mark?

I bet your thermostat is bad/lazy.

isfdude

iTrader: (11)

Post a video of it cold and warm.

CMV991

Will try the stethoscope. Since I don't hear it until accelerating, never really thought to investigate at idle. There could definitely be issues with thermostat reading, although have to say, its always been very consistent. After 4-5 min, heat blows nice and hot. On these 28F - 40s days, the gauge only reads slightly above the 1st mark! In summer, when it warms up and reads close to where it should be, the "knock" is least noticeable. Will shoot with temp gun and check actual engine temp.

Again, I really don't hear it at all until accelerating onto main road. The colder the outside temp, and less warmed up the car, the more noticeable the "knock".

Again, many thanks to all who responded. The more I learn before taking it for repair, the less chance of getting ripped off!