humming noise after replacing the alternator

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lan_baba

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Ok, 2014 is not a good year for my 2006 Lincoln LS, with 95K miles on it. At the beginning of the year, the cold weather cracked my coolant parts and it is leaking. A few months later it is the high pitching noise and it is the pulley and the alternator. Now just less than one week after I have the alternator replaced by the dealer, it comes to this:
When the car first got started, everything is ok. but once the temp is up, I can hear a really loud humming noise coming from the engine compartment. It doesn't matter it is in N, P, D5/D4, the noise is just there, regardless the speed of the car, or even parked. As long as the engine is running, the noise is just there. And the temp is not stable. Normally the temp is at 50%, but now the temp is shooting up the 75%, and down a little bit, then up, down, just swing around 60~75%.
I was guessing that when dealer replaced the alternator, they must have touched something and cause the problem. But before I put my serious face to talk to them, any suggestion what causes the noise?

:confused::confused:
 
Sounds like your fan is running on high all the time......

Are you ABSOLUTELY sure the system is fully bled??
 
Are you sure it's the fan or the new alternator? It's possible that the new alt is defective. A bad alternator can make a whining sound. Unless you specified that they were to use a new alt they may have used a rebuilt. It may be rebuilt anyway depending on whether or not Ford still has any supply for them.

Is the radiator fan running when the AC is on? I can't think of anything that can affect the cooling system that would be affected by removing the alternator as the only thing even remotely connected to cooling that has to be pulled is the AC cooling hose that runs under the rad support has to have its brackets removed so the hose can be moved out of the way but this would not affect the engine cooling system. A defective alternator that can't crank out the juice would though.

You can try bleeding the cooling system on your own, it's simple enough. There's a procedure on the board here somewhere.
 
Shot in the dark here... no real personal experience of my own on an LS doing this but on other cars a temp all over the place and the sound you describe could be a water pump on its last legs.
 
zrxinch said:
Shot in the dark here... no real personal experience of my own on an LS doing this but on other cars a temp all over the place and the sound you describe could be a water pump on its last legs.
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This is possible, but the LS is EXTREMELY sensitive to air in the system. There's a much greater chance that air is the problem, than a bad water pump.
 
Telco said:
Are you sure it's the fan or the new alternator? It's possible that the new alt is defective. A bad alternator can make a whining sound. Unless you specified that they were to use a new alt they may have used a rebuilt. It may be rebuilt anyway depending on whether or not Ford still has any supply for them.

Is the radiator fan running when the AC is on? I can't think of anything that can affect the cooling system that would be affected by removing the alternator as the only thing even remotely connected to cooling that has to be pulled is the AC cooling hose that runs under the rad support has to have its brackets removed so the hose can be moved out of the way but this would not affect the engine cooling system. A defective alternator that can't crank out the juice would though.

You can try bleeding the cooling system on your own, it's simple enough. There's a procedure on the board here somewhere.
Click to expand...

No new alternators available.....

IMHO, the key is the apparent engine temp:

....but now the temp is shooting up the 75%, and down a little bit, then up, down, just swing around 60~75%
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Tnanks for all the suggestions. I was looking at my service records and the dealer said that they bleed the cooling system when they replaced those faulty cooling parts and hoses, and I don't have any humming noise in the months before they replaced the alternator. And the alternator they put in, when I turn on the ac or turn it off, no change of sound. the old one will make a really big difference when ac is engaged.
still scratch my head why fan is at full speed, cause the temp is higher than normal? then must be some thing wrong with the cooling sys.
 
lan_baba said:
...
still scratch my head why fan is at full speed, cause the temp is higher than normal? then must be some thing wrong with the cooling sys.
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It's this. The LS is actually starting to overheat even before the needle moves past the halfway mark. You have a cooling system problem. If they didn't replace all the plastic parts, then another part has started to fail. This will continue until they have all cracked.
 
Ok, the dealer find the thermostat is stuck. But, the mechanic said he still cannot lower the temp enough to make the fan not blowing at full speed, he can only make the temp stable at 50%, but fan blow at full speed after the thermostat got replaced. He checked the in temp and out temp on the radiator, the difference is 40 degrees, so he think the radiator is in good condition. He said maybe a dying water pump, but cannot confirm without take it apart. Any suggestion guys? I need to find a second job to cover all those expenses or anyone know some good and cheap mechanic at the tampa bay area?:mad:
 
I'm still betting it's air being sucked in through cracks. However, the water pump is cheap and easy to replace.
 
Most def not throwing an insult but it has got to be very expensive owning an LS and having to pay a mechanic...
IMO the LS is more of a DIY type of car.
 
well the LS was designed to be bought by people that would probably never open the hood themselves...


so its not really a DIY car, its more of a "you better have plenty of money to pay for repairs" kinda car.
 
1LoudLS said:
well the LS was designed to be bought by people that would probably never open the hood themselves...


so its not really a DIY car, its more of a "you better have plenty of money to pay for repairs" kinda car.
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More of a trade-it-in every 3 years kind of car. I can't think of a newer car that isn't expensive to repair these days. Parts and labour keep getting more and more expensive. Dealers around here are about a buck and a quarter an hour!! Even most indies are around $95!
 
Ok, I think I will give you guys an update after one week.
The temp gauge now is stabling at ~50%, but the fan still kicks in at full speed randomly, most of the time when I stuck at traffic or driving at low speed. So I took the car to the dealer on Monday and expecting them to replace the water pump and everything back to normal. Instead, they did a pressure check of the cooling system and said there is NO need to replace the water pump, the car is just working as designed so I'm good to go. Except, I do NOT want that humming noise!
Do I have any options, or talk to another dealer (I really don't want to)? Is it possible that the coolant flows at a lower speed will cause the problem, which means that I have some clogging inside the cooling sytem? Is there a way to test the flowing speed? Or declog the cooking sytem? Any other suggestions?
 
How did the coolant look when it was drained. If it looked good, then it's probably not a clog. If it looked bad, it could be. Also, check for dirt between the AC condenser and the radiator.

I've learned the hard way, that a pressure test won't always find a leak. I chased one for a while on my 04 that would only happen while driving. I couldn't make it happen while it was sitting still no matter what I did, including pressure tests. It was an exception in that it wasn't one of the plastic parts, it was one of the rubber seals between a plastic pipe and the engine not fully sealing all of the time.
 
The coolant looked not bad when it was drained. And, how do you check the dirt on the condenser? I think it is hide behind the engine itself, hard to see at all.
BTW, how do you find out the problem if the pressure tested ok? Sorry, so many questions.
Maybe I should change the all the remaining cooling system parts, start from the degas bottle.
 
lan_baba said:
The coolant looked not bad when it was drained. And, how do you check the dirt on the condenser? I think it is hide behind the engine itself, hard to see at all....
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You have that backwards.
It goes like this:
Front bumper, grill, condenser, radiator, engine, firewall, dash, driver, ....
Anyway, take the plastic trim over the radiator off to get a better look.
 
Oops, I think you were talking about the evaporator. Anyway, I checked the gaps between the condenser and radiator, a little debrie, and I hosed it out. Still doing the same thing. Ahhh.

joegr said:
You have that backwards.
It goes like this:
Front bumper, grill, condenser, radiator, engine, firewall, dash, driver, ....
Anyway, take the plastic trim over the radiator off to get a better look.
Click to expand...
 
Waking up an old thread - recently noticed an occasional humming noise that would start while driving and go for 1-2 minutes then stop. First couple times it sounded like it was coming from the front passenger side area under the car but other times from the firewall area mid-to-passenger side which is likely the same thing (just sound travel). Possibly a fan or motor running?

A couple times I noticed the temp gauge went up to the 3/4 level but came back to the middle on it's own after about 2 minutes.

No other issues observed and cannot tell what's triggering the 2 occasional symptoms so far.

At least warmer weather is here to start investigating/chasing it down.
 
The humming is probably steam entering the degas bottle. You have cooling systems problems, and they are probably the same as everyone else. Fix it.
 
joegr said:
The humming is probably steam entering the degas bottle. You have cooling systems problems, and they are probably the same as everyone else. Fix it.
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Yeah, happened a couple times to me, asked the wife if she noticed it before (she drives the car more) and she said no because that stuff only happens when I drive the car ('cuz I drive it harder) :slam
 
The fan turns on and runs at high speed periodically which is what is causing the noise - when the fan runs at high speed like this the temp gauge moves higher from the 50% mark then moves back down when the hi-speed fan/humming stops.
 
lsintoronto said:
The fan turns on and runs at high speed periodically which is what is causing the noise - when the fan runs at high speed like this the temp gauge moves higher from the 50% mark then moves back down when the hi-speed fan/humming stops.
Click to expand...

Your engine is over heating!
 
Yup as soon as one coolant part goes bad (except dccv) then you should replace all coolant parts. This is rule numero uno with the LS right after replace all coils and plugs when one goes bad. That sound you hear are micro cracks in the cooling system and pressure test seems to never find anything on the LS.
 
I'll start lining up those parts for replacement. Dealership said it may 1.5 hours of diagnostics to determine the problem - does that seem high (I would assume if common symptoms/issue they could get to the route faster than that?
 
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