Noise & Smoke - Strange Problem

Hello guys,

I'm glad to find you and hope we will share good time and knowledge together.

I driver Nissan Maxima J3.0 2000 model that I bought 2nd hand in 2012. By today, I has done 423,150 km. Amazing car!

A month ago, I replaced the steering pump (bought new) and rack (from scrap). I resolved a major leakage problem, and the car became great too.

Last Tue evening, I travelled from one city to another and came back (120 km * 2) with no noticeable problem. Till I was adjusting it in the parking slot at my home when suddenly I heard some noise. I finished the adjustment and opened the bonnet. I sounded like coming from where the drive belt is. In a minute smoke came. I switched it off, looked carefully, but could not find anything.

In the morning (Wed), the sound came with the smoke for a couple of minutes before the smoke disappear. I drove to the workshop.They suspected some pulleys, but then removed the belt and put it back. The problem disappeared.

In the evening I drove again to the other city with no noticeable problem. But when I switch it on to come back. It produced the noise again, and after a couple of minutes the smoke came. I waited for it to go, but it did not do. I drove back and stopped to fill in petrol. There was noise but no smoke. At home, there was both smoke and noise.

In the morning (Thu), I drove to the WS and change the belt (cracked) and the tensioner/idler pulley (makes a little sound when rotated by hand), but did not solve the problem. Someone said it could be the steering pump (I hope not), another said the alternator inner bearing and another said the belt might have tightened too much and damaged the alternator pulley. These sayings are in different garages.

What made more sense to me is that oil drips onto the exhaust from the rear head gasket and burns, as far as the smoke is concerned. But what I don't understand is that why the gasket blew at the very same time as the other problem with the noise!!

The car has the engine oil leaking a little bit for a long time from different places. I use 10K interval oil and change it almost every 2 months, and never went below the minimum level, although I put 4 litres only! I noticed that the front gasket leaking more than before (I guess). How come? 2 gaskets and the noisy problem all at the same time! What a coincident!!

I travelled in the evening to a 3rd city (185 km), and tonight I have to go back to my city.

I need to discuss with car savvy people to make more sense of what is going on and decide on what to do. Can you share your technical thoughts?

Thanks a lot!

...Someone said it could be the steering pump (I hope not), another said the alternator inner bearing and another said the belt might have tightened too much and damaged the alternator pulley. These sayings are in different garages....

What made more sense to me is that oil drops onto the exhaust and back head gasket and burns, as far as the smoke is concerned. ...

- Tighten the head gasket screws. Add oil seal swelling additive.
- what oil do you use? Some oils do leak, some wont... find the right one.
- Belt off, all appliance bearings have to be checked by experienced maint guy, no guesswork allowed. When all set and done, you check the belt tightness: the belt has to be loose/tight enough so that u may bend it sideways 90degrees with your fingers. Replace belt every 60k. If belt is just a bit too loose, you hear a short whine first thing in the morning - at startup... No noise allowed at any time. Use only new Gates -belt, throw all used belts out the windows.
- if underbelly shield is missing, you get flyin sand wedged into belt grooves. That destroys belts and pulleys. Check.
- Maxima guy is a lucky guy: When Renault scenic alternator accessory belt goes, it shoots through plastic into cam belt area and engine totaled just like that: BANG.

- Tighten the head gasket screws. Add oil seal swelling additive.

- Belt off, all appliance bearings have to be checked by experienced maint guy, no guesswork allowed. When all set and done, you check the belt tightness: the belt has to be loose/tight enough so that u may bend it sideways 90degrees with your fingers. Replace belt every 60k. If belt is just a bit too loose, you hear a short whine first thing in the morning - at startup... No noise allowed at any time. Use only new Gates -belt, throw all used belts out the windows.

Thank you Nahkapohjola for the great info!

Let me understand you better ..

So what I understand from you is that belt tightness has some range within which it remains acceptable or at least not dangerous. Is that correct? I'm trying here to possibly eliminate the probability that the 1st mechanic might have tightened it more that it should that it destroyed the alternator bearing.

The noise which I was talking about is called whine, I guess so. I'm a native speaker. I think you mean the short squeal (high-pitched sound) of the belt in the morning, don't you?

Lastly, what is the possibility of oil getting into the alternator and damaging its bearing? I don't see the oil leaking from the front head gasket going any further than the front side of the engine block.

belt tightness has some range within which it remains acceptable or at least not dangerous. Is that correct? I
- true
- bending 90° -test is adequote measurement

The noise which I was talking about is called whine, I guess so. I'm a native speaker. I think you mean the short squeal (high-pitched sound) of the belt in the morning, don't you?
- morning=cold rubber is harder, slips more eagerly. Yes, short squeal... This tells that belt is a little bit loose.
- if squels every time u push pedal = belt too loose, tighten asap.

- english is hobby for me :(

Lastly, what is the possibility of oil getting into the alternator and damaging its bearing?
- no danger. Bearings are sealed and besides oil never harms bearings.
- If u sink it in oil, it would still work (belt not). Water, flooding road - destroys it via shorting
- If belt is really too tight, then possibly bearings may go.
- Alternator brushes, bearings generally last 150-200k kilometers, or 100k miles. Easy swap.

- english is hobby for me :(:)

- no danger. Bearings are sealed and besides oil never harms bearings.
- If u sink it in oil, it would still work (belt not). Water, flooding road - destroys it via shortingSomeone told me the same thing. This leaves us with no idea why those bearings were whining, doesn't it? I washed the engine and radiator with high pressure a day before that happening, but nothing went wrong at the time!

- Alternator brushes, bearings generally last 150-200k kilometers, or 100k miles. Easy swap.Really? If that's the case, then is it easy to replace only the bearings (wich are cheap) or you have to replace the whole alternator (which is too expensive)?

I have a surprise for you also.

50% of the time when I park the car and before turning off the engine, I get off it and look at the front side to see whether there is a smoke or not. I haven't seen it for almost a week.

And last Wednesday evening, the alternator became quiet! Till now it is still quiet :) I don't know what happened. I asked the mechanic who told me that the oil must have damaged the bearings. He said that oil must have loosened the grease and then left it so the grease tightened again!! I don't know how true that can be.

Also, I was mistaken in my understanding of what some mechanics told me. Because of language barriers where I live. Actually it is the tappet gasket, not the head gasket. I could see a lot of leakage in the front side before, but now it's almost dry.

I don't know what explanation we can give to why this happened and why it's gone by itself, and why the smoke and whine came together and almost went together!!

"I washed the engine and radiator with high pressure a day before"
- washed with high pressure oil? What kind of 'wash' is that... NO: High pressure water surely can find its way into a bearing and damage it. Then you also get shorts in all the zillion connectors. NO.

- bearing change needs extractor, DIY or buy. Cheap. Bearings cost 10$ apiece. A reman alt tend to blow after warranty gone. One issue in them is grounding which is lost due to case oxidation. Grease + add extra gnd cable.
- If u want to keep on the road, take original alt off, open, change bearings and the brushes. Clean out all shorting soot (from worn brushes).
- I had a writeup (see topic below) how to do this. Now has been deleted. Too bad if ppl repair their old vehicles...

- oil leak is typical; seals shrink, screws may get loose. Tighten

- If there was a loose bit, sand or whawtever causing noise, now flown off?
- or then the bearing is shot, last silence before dying?
- everyone has a diff story. We do luv em. Someone of us might get it right.

- no oil leaking? Well, add immediately sm new before all is silent under da hood.

- washed with high pressure oil? What kind of 'wash' is that... NO: High pressure water surely can find its way into a bearing and damage it. Then you also get shorts in all the zillion connectors. NO.What I understand is that the symptoms of my car are not of a short-circuit, are they? And what are zillion connectors? And how do you recommend washing an engine and radiator?

What I understand is that the symptoms of my car are not of a short-circuit, are they? And what are zillion connectors? And how do you recommend washing an engine and radiator?

No shorts as far as your story goes. Water doesnt mix well with harness connectors.

Just engine block, tranny block dirt should be power washed with appropriate cleaning solvent. Never water-power-wash whole engine compartment as various sensors and connectors may short due to water seeping in. Otherwise use air blast in cleaning. Electronics, wiring should stay dry when possible. Alternator cleaning: electronics cleaner fluid plus air blast. If flushed well, ol alt may become free of short circuiting dirt particles from worn brushes.

Your car contains an 80's computer facility building compressed under da hood :(