Problem with FJ75 3FPetrol

[spudman]

i am having problems with my troopy when i start all OK for 1-2 minutes then develops bottom end knock, have pulled off all journels and look like new told by so called expert it could be pressure valve in oil pump replace and still no fix. has anyone had same problem?, next step is big $$$$$ - changeover short block. or does someone have a secondhand motor/block for sale

[Big_Kev]

How bad is this knock?
It sounds funny that it would run good for two minutes without a knock.

[spudman]

i think the knock could be from a CAM journal but the mechanic said this was impossible, but i am only a bloody fisherman. the knock is not loud enough to be a bottom end (piston) the confusing thing it only comes in after the motor has gained oil pressure around 25psi

[blaze]

Hi spudman
more info needed
seems to me that 25psi is low for oil pressure.
If it is a main/bigend bearing, some times just by looking you cant see damage, it needs to be measured with a micrometer.
oil thins out as it gets warm and it is normally when these noise occur
How long have you had the cruiser
has the "knock" devoloped over a period of time. How long?
does it sound consistant with the motor revs or maybe 1/2 motor revs.
As silly as it sounds, go to your local toy shop and buy a kids doctor kit with a stethascope, remove the little plastic bit that you hold on the ticker and replace with a metal rod about 10 inches long. Now start your engine and play doctors, hold the metal rod on the engine and move it about and then you will be able to pinpoint the noise for a better diagnostic result,
MAKE SURE YOUR HAIR ETC ARE NOT IN DANGER OF MOVING PARTS (LIKE THE FAN AND PULLEYS)
When you have done that let me know what ya find
cheers
blaze

[Big_Kev]

It may sound silly but these motors can develop funny knocking noises that come from the cam gear.
I have seen 2 instance's now.
Running the engine with the gear cover removed will diagnose to see if the noise is louder then.
A new cam gear on the front of cam to rectify.
But also only 25 psi oil pressure is low.
Find out what it dhould be and test it with a good master gauge.
When you pulled off the journals did you plastigauge the bearing to qualify the clearance? And was all oil removed from the bearing for the process? (ie;all oil wiped away so it does not interfere with the measurement)
Cheers Kev.

[spudman]

Promlem solved, got a reco motor

[blaze]

what was the prob with the old one
cheers
blaze

[spudman]

elongated pistons, according to the mechanic it must have gotten pretty bloody hot at some stage and the moron couldn't read a gauge, or just didn't care (ex hire vehicle) "thanks everyone for your replies"

[blaze]

thanks
nice to know reasons and outcomes
cheers
blaze