Engine sounds like plane on take-off

[SaabScott]

Just as I was returning to the office today, I noticed that I was getting a lot more noise from the engine than normal.

I've heard this before on cold start, but only for a very short while. I've heard it on a lot of other trucks before and always wondered what it was.

Now, the noise is constantly there, but alters depending upon the RPM's. I'm thinking it is the cooling fan, but I'm still a noobie when it comes to the 5.3L engine and these trucks in general.

Any thoughts?

 

[SaabScott]

Next question .. if in fact it is the clutch on the fan, other than robbing me of power, will it hurt anything (other than my ears) between now and when I get it fixed?

 

[The_Roadie]

Can you fill out your profile to remind us of the year? And how many miles?

In general, except for a bit more stress on the water pump bearing you will be perfectly OK to drive that way. People do it all the time sometimes for a year if they're numb to noises or too cheap to fix it. It will cost a bit in fuel economy, which is why a long repair deferral is misplaced frugality.

You can confirm it's locked on by trying to stop the fan carefully using a rag on the edge. Unless the engine is in overheat mode over 240F, it's easy to stop the fan using a rag.

 

[SaabScott]

Thanks Roadie. Haven't been here since the changes were made. All is updated now.

2006 Saab 9-7X 5.3i, just about to turn 200,000 kms.

Strangely enough, even though I went out after it started doing this and it STILL did it then, after I left the office heading home, it stopped doing it! Weird!

Going to dig into the e-fan conversion now ... I was blown away by the amount of power I was robbed of when the fan was engaged!

 

[The_Roadie]

I've done the detailed numbers before for efan power. I think a summary is that if you have efans that draw 50 Amps, which is huge, then the alternator has to steal ONE HP from the engine to deliver about that much energy.

50 Amp efans are about the same amount of airflow as the stock fan, but let's say you think the stock fan steals TWICE as much energy as the efans. That's only TWO HP. And that only happens when the fan clutch is engaged and calling for max power transfer from the pulley to the fan, and that does not happen at idle, and it doesn't happen at WOT right away. It only happens when the coolant temp gets well above 220-230F. The table that runs this function is easily found using EFI Live or HP Tuners.

So the stock fan with a working fan clutch is only spinning with residual friction,and can be easily stopped with a rag.

Why folks conclude the electro-viscous fan clutch is ROBBING them of 10-20 HP I'll never understand.

 

[SaabScott]

Wow ... that certainly does put things into perspective. Of course, my foot wouldn't press down on the accelerator pedal as hard as when the fan WASN'T engaged ... it is possible that it was all in my head. ;-)


Next question ... does anyone know of a club in Toronto for this platform?
Yes, I am the President of The Saab Club of Canada, but there are so few Saabs and I likely know more than the average owner already. It would be good to connect with folks who know more than I do.

 

[The_Roadie]

How many of the Saab web forums are owned by Vertical Scope?

Are you listed here: http://www.saabsunited.com/clubs

They look independent.

As does saabclub.com

Looks like they Borged this list of poor sods:

Saab92x.com
SaabCentral.com
SaabLink.net
SaabScene.com

 

[SaabScott]

The Saab Club of Canada is listed on most Saab forums, including Saabs United.

Saab Central was the first to be taken over and almost ended up like Trailvoy. Strangely, they've been very hands off the past couple of years and that site has maintained most of its members.
VS did prompt a number to leave and thus SaabWorld.net came to life (I had a hand in that).

Our club site will never be taken over by anyone as our club is a fully registered not-for-profit organization and we have no intention of relinquishing any rights to anything we own/run. ;-)


I can't seem to find a GM truck club in Toronto though ... strange.

 

[Mooseman]

GM's electric-viscous fan was a complete failed experiment. So much that they reverted to a good old fashioned thermal fan clutch in 2008. You could swap in an 08 fan clutch if you got a tune and have the fan error codes turned off.

Having said that, I did go with efans (check my sig). Would I do it again? Depends. The thing with efans is that I have to be proactive as I haven't really found a good way to have them turn on with the A/C so I have to turn them on manually. But PCMofNC (formerly PCMforLess) will be able to control your fans directly with the PCM using their kit and patch for the PCM.
http://www.pcmofnc.com/index.php/product/113-trailblazer-v8-ls1-dual-fan-conversion-kit
or this one for two speed fan operation:
http://www.pcmofnc.com/index.php/product/823-trailblazer-v8-three-relay-ls1-dual-fan-conversion-kit

I do agree with Roadie that their claims of 12-18RWHP loss is exaggerated and even 1MPG increase is pushing it but I think that there are some savings to be gained over a long time. Mine hardly ever came on during the winter. Why else would GM have gone to efans themselves on their full size trucks? I just like having the engine bay opened up, which was especially good for me as I replaced my alternator 3 or 4 times, making it much simpler.

I just picked up an 05 Uplander set of fans from Kenny U-Pull (read "cheap") which might be a bit better as the shroud is spaced a bit more and might have a bit more CFM. I'll update my efan thread when I try these out.

 

[BlazingTrails]

It would actually be very simple to turn the fans on with the a/c. just run your compressor voltage+ to a relay and then come off the relay to your fans and the compressor. obviously you would have to feed 12v+ with a fuse from the battery to the relay.

 

[jimmyjam]

a couple of points that are missing from this conversation
ecm controlled efans turn off >~30mph
current draw of ls1 fans =~10A. ~20A peak at startup. 50A? wha? my dual spal fans pull ~25A once they're spinning (peak 50A for 1/4sec maybe).

with V8 ecms (and 08+ i6) they can be wired to lo/hi speed operation for <5A current draw (ls fans) for normal operation. I can't recommend the 3 relay harness enough. i have mine set to low speed until 207* then high until it drops to 196*, i find this to yield a reasonable hi/lo duty cycle.

obviously if you look at the size and pitch of the stock fan blades vs efans clearly the clutch fan has a much larger cfm capacity at full speed. if you tow, stay with a clutch fan.

lt/ls fans are a good, economical option. AVOID dorman knock offs. I've had them fail, stripped the cheap notched shaft, OE fans are better designed. the key is applying weatherstripping to the fan to create a good seal to the radiator. makes a WORLD of difference.

personally, i wrench on my truck too much to deal with that g.d. clutch more than once

 

[The_Roadie]

current draw of ls1 fans =~10A. ~20A peak at startup. 50A? wha? my dual spal fans pull ~25A once they're spinning (peak 50A for 1/4sec maybe).

I just chose 50A as a huge number to come out approximately 1 Horsepower. (50A X 14V = 700W. 1 HP = 746 W). If people look at efans and think - those things are running off less than 1 HP of electricity, then they should be wary of claims that the mechanical fan is "wasting" or "stealing" 15-20 HP from the engine because the mechanical fan certainly doesn't look like it has 15-20 times the CFM.

If the efans are really running at 1/3 or 1/2 HP, then the claims of mechanical fans stealing 15-20 HP are even more ludicrous.

It was a way to make the efans look better thermodynamically (if the real world current is less than my cap), and put my 2 HP estimate of mechanical fan power into perspective. Heck, people understand what sort of airflow you can get from a puny 5 HP lawn mower. A 15 HP lawn tractor has enough power to do the lawn AND ride you around with a beer in your hand and climb hills. Why is it they believe folks who say the mechanical engine fan is driven off a serpentine belt with as much power as a lawn tractor?

 

[Sparky]

I think it is fair to say anything creating constant drag on the engine, that could be removed, can only improve efficiency (even if only a tiny bit). Clutch fan always causes drag as long as the engine is running.

How much impact there is, well, not that much more than likely, as has been stated.

That said, I fully intended going to efans if my clutch ever went out, if for no other reason than to not deal with that clutch again and to get a little more space in my engine bay. Funny thing is that at nearly 200k miles my stock clutch is still going strong.

 

[The_Roadie]

...Clutch fan always causes drag as long as the engine is running...

I'm not seeing how it's a huge drain. Unless the clutch gets engaged by a temp a lot higher than 210, you can stop it with a rag on the edge. A few ounces pressure only. It looks like it's spinning fast, but that's residual friction in my experience.

A truly comprehensive analysis would include the wind force of the air that gets through the AC condenser and the radiator, blowing through the fan blades and plenums. I believe that parasitic force exceeds the parasitic rotational force of the fan clutch, but I'm not an M.E. just a E.E. who took a few mechanical courses.

 

[Sparky]

Like I said, not a huge drain at all, no, but still a drain nonetheless. But good point, I wonder how much of that is negated by the force of the air at highway speeds

 

[The_Roadie]

The efans may even be driven by incoming airflow faster than the motor RPM at rest. Thus turning the efans into generators that steal vehicle energy and return it to the battery like a windmill.

Like airliners have RATs (ram air turbines) that extend into the airflow to give some electric and hydraulic assistance in case of simultaneous engine failures.

 

[Mooseman]

It would actually be very simple to turn the fans on with the a/c. just run your compressor voltage+ to a relay and then come off the relay to your fans and the compressor. obviously you would have to feed 12v+ with a fuse from the battery to the relay.

No, not really as the fans would cycle with the A/C clutch which would create a really big current draw with the clutch and two fans on engagement. Only way to avoid this would be to add some sort of delay system that would keep the fans on for a time, long enough until the next clutch engagement. There is one high end controller that does this. Another way would be to wire a trinary switch on the high pressure side. I am searching for an adapter for the high pressure port to add the switch. This would also turn off the fans when the pressure is low enough while cruising.