Why is my thundercat engine noisey after a new cam chain tensioner & only when cold?chain is OK.

check valve clearances is an easy job but those engs are very buzzy have a harmonic vibration which u can get moved out of the rev range may b check the cam chain tensioner even mod it to stop it sliding back on the teeth so it cant loosen ya could look into a dynojet carb kit it wakes them up and smoothens out the power ?

Hi, depending on engine fitted it is most likely the cam chain tensioner has collaped or failed. On a twin cam engine like a 1.8 t or a 32 valve V6 there is a chain driving a second chain in the rear of the cylinder head. These chains are tensioned by a oil pressure pressurized piston pushing on a bridge under the chain.

If it collapses, the chain/s become very loose and you will hear a loud clacking noise. It can also collapse due to low oil pressure.

VW is familiar with this problem and the repair involves first checking oil pressure, cold thro' warm. If it is around 85 to105 psi cold and 28 to 35 psi warm at idle, then this indicates tensioner piston is faulty or tensioner guide has broken off.

If oil presssure is good and engine is running synthetic oil...as it should ...then tensioneris suspect. I have also seen these engines with the screen under the tensioner partly blocked . If on removal of valve cover prooves tensioner has collapsed or guide shoe broken or warn then a new tensioner must be installed.

If oil pressure is too low at under 12 psi at warm idle then oil pump is worn and/or engine is worn. Also low oil pressure can be caused by fuel in the oil making it very thin.

If the screen under the tensioner is partly plugged up, then the oil pan must also be removed and cleaned out otherwise plugging will happen again.

To remove and install the tensioner a SST ( Special Service Tool.) is required to compresse the tensioner piston to allow it to be removed from under the cam chain and again compressing the new tensioner to be installed. Cams or chain do not need removing on this job.

Most import shops can handle this as long as they are equipped with the SST tensioner tool.

Sorry, but you will have to change the chains..if you have more then 50k mils on it.

open the clutch plates cover..you will find the tensioner..

Get Ford timing tool kit, part = otc-6488 (For about $119 USD on eBay)

4 timing chains (3 front including the optional balance shaft chain + 1 back)

2 cam guides (1 front + 1 back)

2 oil tensioners (1 front + 1 back)

1 jackshaft tensioner (1 front)

1 jackshaft guide/cassette (1 front)

1 balance shaft tensioner (1 front) (will probably be ok, so dont replace it)

1 balance shaft guide (1 front) (will probably be ok, so dont replace it)

new sprockets + bolts + gaskets etc.

new spark plugs + throttle body cleaner + lithium grease spray + oil change

head gaskets

some of these parts (the front stuff) can be obtained as a primary timing chain rattle noise kit Part# = 2u3e-6d256-** ab for 4*4 & bb for 2*4.

The kits also have later part numbers for us$ 76 @ http://www.fordpartsonline.com

My parts order (without the balance shaft stuff) was:

$76.04 KIT-TENSIONER TIMING 2u3e-6d256-ab

$47.93 Engine, Camshaft and timing, Timing chain, TIMING CHAIN, Explorer, Mountaineer, Rear - 4.0L SOHC - 4.0L SOHC

$57.36 Engine, Camshaft and timing, Chain guide, CHAIN GUIDE, Explorer, Mountaineer, Jackshaft To Cam - 4.0L SOHC - 4.0L SOHC

$103.22 Engine, Overhaul gasket set, OVERHAUL GASKET SET, Explorer, Mountaineer, Upper (Valve Grind) - 4.0L SOHC - 4.0L SOHC

$28.93 Engine, Camshaft and timing, Tensioner, TENSIONER, Explorer, Mountaineer, Upper - 4.0L SOHC - 4.0L SOHC

Its worth mentioning that this procedure is not enjoyable at all and should be undertaken with at least 8 full days to completion (I recon you could do it in half the time the second time).

It is basically on entire engine re-build with both heads off and the engine out of the vehicle.

It is not possible to do the rear chain or sprocket with the engine in the car as the flywheel needs to come off + at least 1 head, but it is possible to do the front primary chain and or front cam chain with the engine in the car.

You will be a ford exploder and timing expert after you do this - the main reason should be the love of your American built vehicle. Its a solid car - except for the plastic guides!

Disclaimer Note: This is how i successfully did the job, but i am not a ford mechanic and don't hold me responsible if this does not work for you.
Timing Overview

A Small Sprocket on the crank turns a larger (2 to 1 ratio) jackshaft sprocket that is in turn connected front & back to the 2 camshafts.

Thus a 360o turn of the crank will turn both the camshafts 180o.

Firing order is 1-4 2-5 3-6, Right side numbers 1,2,3. Left Side = 4,5,6.

At TDC pistons 1 & 5 are fully raised, thus 1 is about to spark & 5 is evacuated.

The engine will turn freely (no piston to valve contact) with the cams 180o out, it will even run (roughly) with 1 out 180o, any other settings may cause major damage to the valves.

The 2 cam shafts come with timing markings, "yes" real timing marks that anyone can use (even without special tools) to ensure correct timing.

The way to time it is to ensure both the off centre cam shaft slits are level/flat with the head.

With the engine at TDC both the cams need to have the off centre slot in the same position either up and level or down and level.

It is super critical that both the camshafts are 100% in sink with each other, i.e. not a few degrees off, the engine computer can compensate for crank timing but not engineering failure.

Be warned the camshafts can turn easily fast & hard by themselves as a few springs are compressed at TDC, I got my finger jammed and its still healing + if the engine is not at TDC you may damage a valve.

Now heres the hard thing that you will need special tools for - if you need to change the timing, you will need to be able to undo the cam sprocket bolt on both cams & these are done up real tight.

There is a tool that you attach that has 2 pencil thick shafts that fit into the sprocket and prevent it from turning - then you need to put about 90Nm of force on the bolt (remember the rear one if LHT)

For the $money$, its well worth getting yourself the tool kit - it will save you hours in the long run. Search eBay for otc-6488 should be US $119 - then sell them again for say $100.

There is also a tool version of the oil tensioner in the kit that screws right in and puts the correct amount of force on the chain + guide, to enable you to do up the cam bolt with the chain and sprocket in the right spot on the cam.

Howdy: Depending on the year some FJs have a nut/screw at the bottom rear of the front cylinder. This can be adjusted and it works.
If the chain has not been adjusted in the past the nut/screw may be
stuck with gunk. Spray a little carb cleaner on the nut/screw and let set for a couple houres then try again. Get a manual for that year follow the "cam chain tensioner" procedure. I do not have enough lines to expain the proceedure. Good luck and ride safe - Doug

check that the new cam chain is roughly the same length as the old one, ensure that it is properly installed on the bottom (crank) sprocket, make sure that your tensioner is backed off fully, even after all of this you will still find that the chain seems too short, tip the cam to the left side of the engine & your chain should slip on..double check your cam timing with cam cap snugged down & tensioner released.

If the cam chain jumped then the tensioner is not tight. Timing is way off and valve hit piston. Need to **** case and replace tensioner, dry time then install new piston and pull vales to see if they are bent.

the tensioner is definitely a problem on these bikes

everything is standard thread
loosen nut, loosen screw, slowly turn it in until noise stops, tighten nut.
requires 2 wrenches

assuming you are talking about the cam chain tensioner