: What is the Northstar suppose to sound like?



97Concours1
12-16-07, 02:25 AM
I just bought my first Cadillac as a fixer-upper. It had the Northstar head gasket issue and I repaired it. It runs smooth, but I hear a burble sound in the exhaust note that concerns me. The sound seems to come from the area under the brake booster. Since I have never driven another Cadillac before, I don't know if this is normal. It's not a sharp leaking manifold gasket sound, it's more of a burbling sound. I thought it might be normal because of the sideways mounted engine. The exhaust pulses from the front cylinders have to travel back and join with the back cylinders and can be out of phase. This could cause some exhaust pulses to cancel and others to double. The result could be a burbling sound. The sound is not at WOT. It's at lower RPM under light load and light acceleration.

I remember a similar sound on GMs old Z24s. From the back they had a burbling exhaust sound. I think this was a phasing issue too. With an engine running North/South, all the cylinder pulses travel nearly the same distance to get to the rear of the vehicle. This makes the sound even (I think).

So my question is, what is normal? Burble or no burble?

Ranger
12-16-07, 05:41 PM
I am on my 3rd Northstar and 4th in my family and I have not noticed any sound as you describe. I assume you Timeserted the block when you replaced the head gaskets?

codewize
12-16-07, 11:58 PM
Other than the trademark whirling sound and the ticking during warm-up my engine is very quiet and I have never heard the sound you describe either.

I think I know what you're talking about but I would have to say that it's not a normal N* sound.

Crown Vic Owner
12-17-07, 12:10 AM
is it a burble like this?

bGuXoroykgU


If so, its normal. I think the northstars exhaust is a little open for what it is if you ask me.

CadillacSTS42005
12-17-07, 12:28 AM
rofl
it better not sound like that stock
thats my 97 ETC and ive got a full cat back system on it!

Crown Vic Owner
12-17-07, 12:30 AM
lol, not stock obviously, but is it similar i should say, damnit.


I WISH it wasnt all snowy out, id go start my car and see

CadillacSTS42005
12-17-07, 12:36 AM
lol
i could go into the garage and start the 05 STS or the 97 ETC (74 sounds alot different lol)
both of the Sevilles are outside and the Vs in the other garage

Crown Vic Owner
12-17-07, 12:43 AM
ugh, honestly, are you rich or something.


I envy you.

Either way, hold on, i got a video ill upload

dkozloski
12-17-07, 02:16 AM
ugh, honestly, are you rich or something.


I envy you.

Either way, hold on, i got a video ill upload
He's one of them pampered brats. But he's a pretty good guy anyway.

97Concours1
12-17-07, 09:13 AM
is it a burble like this?

bGuXoroykgU


If so, its normal. I think the northstars exhaust is a little open for what it is if you ask me.

Yes, this is what I'm talking about. Mine sounds similar, but not quite as loud (stock Deville). It's probably most noticable around 1500-2000 rpm. Thanks for the video.

It would be interesting to compare the exhaust sound of a newer Cadillac with a Northstar that runs North/South to one that runs sideways. Maybe even compare the XLR or Corvette sound to our cars. I'm guessing that since the distance the exhaust from each cylinder travels to get to the rear of the car is equal (with true duals), the exhaust will sound smoother and even.

97Concours1
12-17-07, 09:37 AM
I am on my 3rd Northstar and 4th in my family and I have not noticed any sound as you describe. I assume you Timeserted the block when you replaced the head gaskets?

Yes, I used Norm's inserts. So far (4000 miles) I don't see any indication that the head gaskets are leaking. Coolant is staying right at the same level and the engine temp is rock solid.

The sound was especially noticable with the intake cover removed. I drove it like this for a while. After I put the cover on it was much less noticable. Also, no one riding with me has ever noticed the sound. It's not very loud at all.

CadillacSTS42005
12-18-07, 08:30 PM
He's one of them pampered brats. But he's a pretty good guy anyway.

aww Koz
i love you too bro

nah i work about 40-50 hours a week to afford my lacs

Crown Vic Owner
12-18-07, 11:45 PM
Yes, I used Norm's inserts. So far (4000 miles) I don't see any indication that the head gaskets are leaking. Coolant is staying right at the same level and the engine temp is rock solid.

The sound was especially noticable with the intake cover removed. I drove it like this for a while. After I put the cover on it was much less noticable. Also, no one riding with me has ever noticed the sound. It's not very loud at all.

Intake cover covering the intake manifold, correct?

97Concours1
12-19-07, 06:12 AM
yes.

smooththg6969
12-20-07, 04:43 PM
I would check to see if the egr tube that comes from the exhaust mainfold is connected to the egr valve/solinoid properly.