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YOUR RESEARCHWhining sound after startup (I don't have kids so it's not that)
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engine compartment fan
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Suspected cause · Original poster
I thought it was the engine compartment fan but discovered today that's not it.
Whining sound after startup (I don't have kids so it's not that)
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Leading evidence: 'engine compartment fan' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'engine compartment fan' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Lubricate bearings as a fix' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
I found this thread on Renntech that talks about disassembling the pump, cleaning it, and lubricating the bearings as a fix.
Whining sound after startup (I don't have kids so it's not that)
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A minute or two after I start my car, I hear a "whining" sound coming from the engine compartment. It sounds a bit like a vacuum cleaner. It runs for a few minutes and then stops. I thought it was the engine compartment fan but discovered today that's not it. So what is making that noise? Enquiring minds want to know. It only seems to happen from a cold start. I have a 1999 C2.
Probably your SAI valve and it's normal.
The Secondary Air Injection System
The secondary air system pumps ambient air into the exhaust stream after a cold engine
start to reduce the warm up time of the catalytic converters and to reduce the hydrocarbon
and carbon monoxide emissions. The engine control module controls and monitors the secondary
air injection system.
The injection pump draws in ambient air and supplies it to the shut-off valve.
An electric solenoid (change-over valve), activated by the control module, switches vacuum to open
the shut-off valve. Once opened, the shut-off valve allows air to be pumped into the exhaust
steam via the cylinder heads. The check valve stops exhaust gases getting back into the air
injection pump when it switches off.
It may just be a noisy, old SAI air pump. My old pump was squealing on startup, probably worn bearings. I purchased a used Bosch air pump on eBay for $75, and all is good. Takes about 15 minutes to change.
Thanks! Now I know what this is. Makes sense. Now I want to listen and see if my Subaru has one of these. If so, I would have attributed it to the A/C system.
I have a 99 C2 as well and sometimes I would call it loud but if you look at the cost of a new pump on a 99 C2, it sounds just fine. As far as I know, the newer pumps cannot be retrofitted to the 99 C2.
The one on my '99 C2 seems on the loud-ish side but I've never heard another one to compare it to. I'm in North County (Leucadia) once in awhile, maybe we could do a socially distanced sound comparison sometime.
Ok. So I�ve thought the SAI on my �99 C2 was loud, but I also had nothing to compare it to. What�s the right part number for the replacement for the 99s?
I found this thread on Renntech that talks about disassembling the pump, cleaning it, and lubricating the bearings as a fix. Seems worth a try to save $1,500.
https://www.renntech.org/topic/34844...n-engine-cold/
I took a video of my SAI pump working. It�s not a squealing noise - more like a vacuum cleaner - but loud enough it drowns out my aftermarket exhaust at idle. Is this normal or the failing SAI pump noise?
https://www.youtube.com/watch?v=LZBPwoHMPg8&feature=share
This is a source reference. Confirm exact model applicability in the original material.
