fan wobble RPM thumping sound when Idle after Timing belt replacement. (1 Viewer)

[Colorplates]

Stock 1999 LX470. 210000 miles.

Hi all. This may be multiple issues, I will try to be as clear as possible.

I purchased the vehicle with 190k and the timing belt had not been done since 90k. There was a small gasket leak as well that needed replacing as well, so I decided to get everything done at once, Timing full fluid/greasing/rehose including T joints, water pump and pully, new plugs, coils were fine.

When I got the truck back from mechanic, two things I noticed that were off. The idle was wavering as if it could not make up its mind about where to rest. I figured this might be due to the computer figuring this out. After about 40 miles on the highway I dumped all coolant and had to pull over with an overheated engine, and fill radiator with what water i had to limp it to safety. Luckily this was a lower hose clamp that had not been tightened well and the hose came off at highway speed. After sorting that out, and yelling very loudly over the phone over several hours I was back on the road.

Upon further review, while making sure my work was sound, I noticed that the radiator fan was wobbling quite a bit, and that the idle sound had a thumpy cadence every revolution.

I can feel a cadence in the gas pedal very slightly at low speed when accelerating as well.

Also, for the this truck, is it normal to experience a loss of power when climbing in altitude? It seems like I have to fight to keep it moving uphill without it downshifting and revving over 3k rpm. I have searched for this too, and have not seen any definitive answer.

I hope that description was thorough enough. And thank you all in advance! I will attach a video tomorrow if I can get out there.

 

[97 AZ LC]

It sounds to me like you should start over with a new mechanic, while lobbying the previous mechanic for a waiver of labor charges.

 

[JunkCrzr89]

Take it back to the mechanic who did a crappy job and have him fix his screwups free of charge. Not connecting a radiator hose clamp and causing engine to dump coolant and overheat is ridiculous.

Wobbly fan = bearing in fan bracket is about to send the fan through your radiator. Fan bracket should’ve been replaced when doing timing belt job.

Fluctuating RPMs at idle = vacuum hose not connected or cracked, intake tube not connected or cracked, throttle position sensor, etc., since all of those things were removed/disconnected when doing timing belt job.

 

[jsigone]

fan bracket bearing.......about 94% if the labor in a tbelt job just to get to it. OEM part is like $220, don't get a 3rd party for this part as they only last 1-2 years where the OEM lasted almost 20.

 

[2001LC]

Possible the 4 fan clutch nuts are loose. It's also possible fan clutch and/or bracket failing. The fan clutch should have been inspected during T-belt job, which is easy to make the call good or bad. Fan clutch can "easily" be inspected and replaced anytime. I say "easily" inspected, if so bad it's wobbling. Just weak fan clutch is more subjective to make the call good or bad.

Tough part on this job: Is what else? Did mechaince just get tried and/or distracted during button up. Or is the whole job full of improper procedure.

A few very common errors are:
Not sealing threat of pulley bolts.
Not putting back, 2 very small plastic covers below fan bracket.
Routing crank positioning sensor and oil sending units wires harness in front of fan bracket.
Routing cam wire harness wrong. Also breaking their, wire retaining clips.
Not tightening fan bracket bolts, through side of A/C compressor.
Not using a torque wrench on every bolt.
Not properly burp air from coolant system.

 

[OwnerCS]

I've found that if the 4 serrated fan clutch nuts are reused, they can work themselves loose causing the fan to wobble. The serrations bite into the clutch shaft to keep them from backing out. If the serrations are worn from reuse, they will not hold.

Serrated nut example below.

 

[shiretowndown]

Possible the 4 fan clutch nuts are loose. It's also possible fan clutch and/or bracket failing. The fan clutch should have been inspected during T-belt job, which is easy to make the call good or bad. Fan clutch can "easily" be inspected and replaced anytime. I say "easily" inspected, if so bad it's wobbling. Just weak fan clutch is more subjective to make the call good or bad.

Tough part on this job: Is what else? Did mechaince just get tried and/or distracted during button up. Or is the whole job full of improper procedure.

A few very common errors are:
Not sealing threat of pulley bolts.
Not putting back, 2 very small plastic covers below fan bracket.
Routing crank positioning sensor and oil sending units wires harness in front of fan bracket.
Routing cam wire harness wrong. Also breaking their, wire retaining clips.
Not tightening fan bracket bolts, through side of A/C compressor.
Not using a torque wrench on every bolt.
Not properly burp air from coolant system.

What would symptoms be of

"Not properly burp air from coolant system" ??

 

[JunkCrzr89]

What would symptoms be of

"Not properly burp air from coolant system" ??

Running hot/overheating.

 

[2001LC]

What would symptoms be of

"Not properly burp air from coolant system" ??

Often your cabin HVAC heat will not blow very hot, it should. Which happen when coolant low. You can overheat as @JunkCrzr89 said. If coolant so low ECT sensor out of coolant. Your gauge may read as if running cool (false reading).

Check coolant by looking in radiator under the cap. Do this after 8 hour cool down, in the morning before OAT get to high. Have front end higher (best) than rear or vehicle level.

 

[Colorplates]

Mechanic replaced whole fan bracket with bearing. I cleaned the MAF sensor, and the truck is purring like a kitten again. Here's to another 200k miles!

 

[super90]

Who was this mechanic.....so others can be aware.....