rich4368

My 2010 GL350 with 89k miles. I performed all DIY maintanence, has been running great except when stopping at the traffic lights in Drive mode hearing loud humming sound. Much like the regular diesel sound but louder. It happens everytime after driving in city with many traffic lights. The first few stops sound norm but after like 5 stops will hear this loud diesel humming sound. Once it starts moving the sound goes away (back to normal diesel sound). I am wondering if this could be the faulty: Idle Air/Speed Control Valve at the Air Injection System? Part is only $40 looks like a DIY.

alx

Check your exhaust. There are couple connector pieces that will rust through and let go resulting in the connected pipe flanges rattle just like you describe it.

rich4368

Thanks for pointing that out, I didn't think of that. I also notice the driver side rear exhaust is a little loose comparing to the passenger side. Will get under the truck this weekend to find out.

chsu74

Check your exhaust manifold. Common problem. One of my bolts was rusted on the manifold had to be replaced under CPO.

https://www.parts.com/index.cfm?fuse...HAUST-MANIFOLD

rich4368

Visually didn't see any join loose or rusted in the pipe. I inspected it about 10k miles ago when replacing the fuel filter didn't see anythimg suspicious. Back then the humming sound already existed.

I did find the engine cover's five rubber damper loose for a while. Will receive them next week see if that reduce the humming and rattling sound. Part number:
ENGINE COVER BUFFER

Part Number: 6420940785

Drebner

I have the same exact noise on my 2011 GL350. It happens only when in motion at speeds of 2-5mph. It comes from the exhaust or even might be sourced from the manifold as previous poster suggested.
I managed to replicate the issue ever ytime when I do power braking. Press brake and gas at the same time and you can hear it distinctively.

I would appreciate any further observations or suggestions on approaching the issue.

rich4368

The noise still exist now with $103k miles. Brought it to indy they still couldn't locate the noise. They checked manifold and exhaust joins said no leak or loose connections.

I have bigger issue now, my engine oil leaks again. The oil cooler was fixed at 40k in warranty. I need to add about a quart each month. Indy said $2-3k to fix. Just replaced the suspension compressor and distributer, cost $1200. Whats next?

Drebner

Yup, seems that owning a 5 years or older GL would be for the ones that don't mind getting dirty themselves. You pay 10k a year to own this car for the first 5 years and after that you pay 10k a year to the dealer to have it running or 3-4k to an indy. The alternative is to be tech savvy and DIY but again...is that all the pride of ownership is all about?
I've spend $500 per year in maintenance on 20 years old land cruiser.
Anyway, don't mind getting dirty myself and certainly can justify the cost to own >5yr GL and looking forward to get all the issues with mine resolved.
Will report when I find out what is the humming all about, as I can't stand anything wrong with any of my vehicles It sux to be me.

About the oil cooler, I had mine done at 40k also. It will be 2k to get an indy to do it. If you don't plan on becoming part time mechanic you should sell and invest in another GL or SUV.
On my to do list is the timing chain which started to rattle for 2 sec when I start cold. This is another 2k done by an indy.

sak335

hey, Drebner, did you end up doing the timing chain? I'm facing the same job and will be doing it myself. Interested in hearing your experience.

Drebner

Yes, got it done and issue solved by replacing the timing chain. I purchased the timing chain kit and it was fished in from the top by attaching the new chain to the old one after the cams were locked in place. Sprokets were nit worned out and nit necessary to replace. It would be a much more comolicated job to remove the valve covers if it was necessary. old chain was stretched and this thing was out of timing ...crazy! New chain made it all better..like new. Issue afterwards was that my indy loosen a screw for the turbo exhaust pipe which caused a whole set of new unnecessary issues but that's another story entirely.

DennisG01

Trying to find a noise that only replicates under certain conditions can be a real pain. I had a noise that was only present under certain throttle settings and/or letting off the throttle. Figured something had to be loose somewhere. I showed my wife how to replicate the sound and I crawled around under the vehicle touching, holding, bracing things with my hand until the noise would no longer sound. That helped since it narrowed down my search area.

As I got closer and closer and I found out it was one of the purple exhaust hangers - approximately just in front of the rear wheels. The hanger is not just rubber (or whatever it actually is), it also has metal inside it to help hold it's shape. The metal had broken and that was causing the noise.

I'm not saying this is anyone's issue, but the process of touching/holding/bracing could help find the culprit.

Drebner

I had same exact issue, took awhile to locate that hook but solved my hard to locate problem as well.

alx

I usually repair exhaust rattles by intelligently cranking the rattle- defeating knob marked "volume" on the radio. Works every time. You poor sobs...

DennisG01

That sounds like a Scotch-induced response!

Ha! Yes, that knob works very well when it's rotated in a clockwise direction. It doesn't work so well in a counter-clockwise direction.

sak335

Thanks for confirming. I'm pulling together the parts and a couple special tools to do the job myself. I still don't fully understand how you pull the chain through with the cams locked, but I'm sure that'll become apparent once I get the valve covers pulled. I know on my race car ( a straight six) that the intake cam freewheels due to variable valve timing, and that the exhaust cam stays stationary when the cams are locked. So it would be possible to change the chain the same way by doing the work from the exhaust side. It looks like in WIS the procedure shows the work being done by the (USA) passenger side bank and that the real key is having the factory (or reasonable copy) chain riveting tool, which can be had for less than $200. If I can do the job for $1000 with tools I'll be happy to have saved the difference given that I expect to keep this POS long term, which probably means doing the job a second time at some point down the road; or if I get fed up I can always sell the tools on eBay.

alx

... and a good cigar

Now on a more serious tone- before tearing up anything remove the cam sensors and look through the holes- you will be able to tell if the timing has moved (i.e. Chain / sprockets are messed up)

rich4368

just a quick update, Indy fixed the oil cooler also flush the trans fluid at 110k about 4 months ago. Paid $2500 and start to like this truck again. Checked timing belt all good, the humming sound went away after replacing the oil cooler and all seals. It is now 120k just got back from a 2k miles round trip. Indy used the new Mercedes engine oil 5-30 229.52, I changed the oil today the extractor seemed slow and realized the used oil was a lot thicker than the old Mobil one 0-30 229.51. I think the truck runs smoother and accelerate faster with 229.51 when it gets to 8-9k miles.

mrduglas

I think that this car will be cool at all times.