Hi all,
i dumbfounded here....i have a 2000 4runner limited w/ about 190k miles....never had any problems with the truck and up to a couple days ran perfectly-no overheat,unusual sounds,no cels,no fluid leaks...
parked it over the weekend and started it today and it sounds like the engine spins freely with out any signs of compression and wont start.
the spinning sounds like it snapped the timing belt but, i openned up the front engine cover and the belt looks good(replaced about 8k miles ago) also checked for timing marks and they all lined up perfectly.
spun the engine by hand(crank bolt) and i could turn the motor w/ less effort and i dont feel compression.
also,checked the oil an it's all clean w/ no contamination(did an oil change 1500 miles ago)....
hope i dont need a new engine on the truck...pls help
thanks

 

I think the belt has to be broken, did you visually see it move?

 

thanks for the reply..
yes,i took the cover off and watched the belt/2 cam sprockets move and actually lined up all the timing marks while turning the crank bolt(pretty much dead on the marks)...
my initial thought was maybe sheered teeth on the t-belt but,all checks out good-gave it 8 manual turns.
while turning the motor manually,it felt loose with no evidence of compression...
i'm doing a compression test tomorrow hopefully the numbers checks out good....

 

i cant think of anything, you spun the motor on the pulley and tried to start it with the starter so that rules out snapped crank, timing marks line up so that rules out snapped timing belt, its unlikely that both cams snapped in the casing simultaneously, the only thing i can thing of is check compression, color and level of oil, and level and color of coolant. this is definitely very odd

 

That seems very strange to me

Broken cam? I'd pull the valve covers and watch everything while turning manually.

Did it make any weird sounds?

 

I would say bent valves but you say the timing marks line up so idk. Thats reallyweird

 

thanks for the replies....
that's why right now i'm scratching my head,all i could think of is a compression test tomorrow and i'll go from there-hopefully no bent valves but,being a non interference engine it kinda gives me hope...
one thing that i do remember when i last started it and ran normal-it sounded like it had a weak battery as i noticed the starter spinning slowly-the truck still started and ran normally-drove it home from the grocery about 20 miles with no issues-parked it and that was it....
oh,i did check the battery voltage and load tested it with my battery tester and it checked out fine...
thanks again for all your help

 

check for fuel, wet plugs are a good indication you have fuel
check spark, a screw driver up the end of the plug lead, hold the screw driver close a bolt on the engine about 20 thou is close enough to see if the spark jumps,

bore wash is common, this is when fuel washes away the fine oil coating on the cylinder bore, causing a lack of compression,
get a oil can, remove all plugs, a few squirts of oil in each cylinder, turn motor over on starter, reinstall clean plugs try starting truck as normal.

if still no start compression test

 

i've heard of bore wash before and will definitely check for that possibility.
what's a good compression figure i should look out for given the mileage on the truck(190k miles)
thanks again

 

i dont know about that truck but i would think that the compression should be at least 150psi or more.

 

okey here's an update and it really doesnt look good....
i did a compression test and all 6 cylinders read as zero/"0"/nada
i even verified it w/ 2 compression testers....same results.
spark plugs look good,no oil/coolant contamination i can see and the engine even doesnt have an ounce of fluid seepage...
pistons are moving as i stuck my magnetic antenna in each cylinder and watched it moved up and down.
i just couldnt figure out how this happenned...truck ran perfect w/ no issues,parked it for 2 days went to warm it up then blown motor? oh i'm the only one that has the key to it....
how can a motor be dead from parking
anyways,anyone have a good low mileage 3.4 motor along the md/dc/va area?
thanks for your replies...

 

According to my Haynes manual, it should have 145-217 psi @ 250 rpm. Last time I checked my compression, my #s were between 180-195 for all cylinders and I have a 3.4L w/ 190K also.

 

As MUNJUE said put a little oil in the cyl.s and then test the oil could have just moved away. otherwise the valves are likely.
Weird that this happened from sitting though. it is possible that the timing jumped and you cannot tell check the crank bolt to see if it is tight make sure that it is tight. then valves.

 

Pull valve covers and verify cams are spinning.

 

that'll be my next test...
how are the cams set up on these motors? i've only seen the early 3.0 set ups...any pics anyone can post to see what i should "normally" be expecting?
thanks again...

 

Verify all four are spinning, should be very apparent if you are having issue.

Goodluck, I'll be watching this thread for the outcome.

 

really appreciate the pic-thanks so much as this is a big help...
i'll keep everyone updated and will take pics too.

 

put a couple squirts of oil down the cylinders, as bore wash will cause a lack of compression,
try this before you pull your motor to bits, it is quite common for toyota's to do this.

the piston rings require oil to form a good seal against the cylinder wall, no oil no compression.

as for a compression reading all you want to see is even compressions as the gauge's are not accurate, if 5 cylinder have even compression and 1 is 40psi down etc.

i have had NEW compression gauges vary as much as 50psi between different gauges.

also you should be able to see the cam spinning the the oil filler hole if you get someone else to flick the key

also you said that the cam marks ''pretty much lined up''
do you mean that they are 1/2 a tooth out 1 tooth out, 2 tooth, 3 tooth etc?

 

ur method is the next trick up my sleeves b4 an official tear down(hope it works)
abt how many drops of oil?
oh and the timing marks are spot on(2 cams marks and crank at "0" mark)
thanks

 

a teaspoon is usually used in inline motors and a tablespoon for V and flat motors