I replaced the timing belt on my 93 caravan with the 3.0 in March, and ever since then, the motor has a knock, which sounds like it is coming from the topside of the engine. It wasn't there until I did the belt, and it has me concerned. I admit I don't know squat about import motors as I am the owner of 2 65 Chevy's, and this noise has me worried about internal damage already done, or in the process of being done. Can someone help me with this?
Thanks for any and all help :help:
96Grand
05-03-2006, 01:58 PM
In my research, after this happened to me last summer, it seems to be the rear cylinder head that is more prone to have (rocker arm shaft, cylinder head bolt that goes through the rocker arm shaft & rockers break) this type of damage.
It can also happen to the front head, but it's more likely to be the rear one.
Once this happens, you may need a completely new cylinder head, if this turns out to be true in your case, I would definetly get the other head machined & have a valve job done.
NOISY VALVES
Possible Causes
High or low oil level in crankcase.
Thin or diluted oil.
Low oil pressure.
Dirt in lash adjusters.
Worn rocker arms.
Worn lash adjusters
Worn valve guides (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872040).
Excessive runout of valve seats (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872043) on valve faces. Correction
Check for correct oil level.
Change oil.
Check engine oil level.
Replace rocker arm/hydraulic lash adjuster assembly.
Replace rocker arms.
Install new hydraulic lash adjuster assembly.
Ream and install new valves with oversize stems.
Grind valve seats (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872043) and valves.
http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OB0~P3R0H~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/56492424/34853941/98952975/62415755
REMOVAL (Front Head)
You will have to remove a few things that aren't in the instructions below to get access to the rear head. Intake Plenum, Windshield Wiper Arm & Cowl etc...
Remove upper intake manifold assembly. Refer to Intake Manifold (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34855755).
Disconnect spark plug wires by pulling on the boot straight out in line with plug.
Disconnect closed ventilation system.
Remove cylinder head cover and gasket.
Remove four rocker shaft bolts and retainers.
Remove rocker arms and shaft assembly.
If rocker arm assemblies are disassembled for cleaning or replacement, re-assemble rocker arms in their original position.
INSTALLATION
Install rocker arm and shaft assemblies with the stamped steel retainers in the four positions, tighten to 28 Nm (250 in. lbs.) . CAUTION: The rocker arm shaft should be torqued down slowly, starting with the center bolts. Allow 20 minutes tappet bleed down time after installation of the rocker shafts before engine operation.
Clean cylinder head cover gasket surface. Inspect cover for distortion and straighten if necessary.
Clean head rail if necessary. Install a new gasket and tighten cylinder head cover fasteners to 12 Nm (105 in. lbs.) .
Install closed crankcase ventilation system.
Install spark plug wires.
Install upper intake manifold assembly.
Don't rule out the following either.
Connecting Rod Noise
CONNECTING ROD (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872026) NOISE
Check engine oil level.
Check engine oil level. Inspect oil pump (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872057) relief valve and spring.
Change oil to correct viscosity.
Measure bearings for correct clearance.Repair as necessary.
Replace crankshaft (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872030) or grind journals.
Replace bent connecting rods (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872026).
Main Bearing Noise
MAIN BEARING NOISE
Possible Causes
Insufficient oil supply.
Low oil pressure.
Thin or diluted oil.
Excessive 6earing clearance.
Excessive end play.
Crankshaft (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872030) journal out-of-round, worn.
Loose flywheel or torque converter. Correction
Check engine oil level.
Check engine oil level. Inspect oil pump (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872057) relief valve and spring.
Change oil to correct viscosity.
Measure hearings for correct clearance.Repair as necessary.
Check thrust hearing for wear on flanges.
Grind journals or replace crankshaft (http://www.alldatadiy.com/alldata/AFI~V6600313~C30621~R0~OD~N/0/41746574/56417202/56417205/56419253/34853741/100411974/34853743/34872030).
Tighten to correct torque.
mcmotors
05-03-2006, 05:55 PM
If you had the belt timed wrong, or if you rotated the engine or cam while the belt was off. you may have a bent valve. Check compression of each cylinder, see if one or more is much lower than the others. Recheck cam timing, and if it is a bent valve , the heads will have to come off.
Chet42
05-06-2006, 03:53 PM
The 3.0 is a non-interference engine so the chances of a bent valve is slim, did you or whoever replaced the belt re-align the cam sprokets properly to the timing marks on the front casting. In most cases a ticking after replacing a timing belt is due to the valve timing not being setup properly. I know i learned the hard way when i did my belt, it ticked like crazy and i ended up having to tear it down again and re-allign the timing marks.
Chet.
93caravan63
05-06-2006, 07:50 PM
The timing marks are lined up about as perfect as can be, but the knockong noise is still there. I tried to pinpoint where exactly the noise is coming from, but I can't tell if it is actually in the top of the engine, or coming from under the cover. The van still has the same pickup, and power as it always had, but it now has the knocking noise. The oil level is where it's supposed to be, as I changed it before we did the belt. it's also got a new transmission in it(2005), so it is mechanically sound.
