Scraping noise from front of engine
#21
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Concerning the pump tightening, the service documentation for the 4.2L (both variants) specifies 9 pounds (108 inch pounds) of torque for the retaining bolts. The pulley bolts are supposed to be single use (because they are stretch bolts) and should be tightened to 88 inch pounds + 1/8 turn.
Ok found them at JLR in Annapolis, MD. Damned expensive!
Last edited by jackra_1; 11-02-2018 at 08:13 PM.
#23
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So took out the water pump and split it into the two halves.
Only two bolts hold these halves together when not installed on car. The bolts that hold the pump onto the engine also help clamp the two halves together.
All these bolts do not touch the their respective holes in the front half of the pump. There is a small clearance. The bolts that screw into the engine block do not touch either the front half or the back half.
They screw into the back half of the pump and are entirely responsible for keeping the two halves aligned with each other correctly. No alignment notches
These two halves only have to be out of alignment a very small fraction of an inch, imperceptible to my eye.
If out of alignment then the impeller will scrape the housing in the back half making quite a noise.
In the pic of the back half if you look carefully you can see scrapes just above the lower lip where the impeller came in contact.
When rotating the assembled unit by hand there is no scraping it only happens under the load of the belt in tension.
So my theory is that if the bolts that hold the pump on the engine are not tight enough the prolonged tension of the belt may be enough to pull the halves out of alignment enough to cause the scraping.
The pump will still function but the noise is too much.
Now I am going to be paranoid about getting the correct torque settings when I install the new pump!
Last edited by jackra_1; 11-03-2018 at 01:37 PM.
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Don B (11-10-2018)
#24
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My water pump is taking the scenic route!!!!! It was promised by the 7th of this month.
- Nov 4, 2018
- 08:00am PST
- In transit
- SUMMERFIELD, TX 79085
- Nov 3, 2018
- 20:54pm PDT
- In transit
- GANADO, AZ 86505
- Nov 3, 2018
- 08:46am PDT
- In transit
- NEEDLES, CA 92363
- Nov 2, 2018
- 20:45pm PDT
- In transit
- LOS ANGELES, CA 90023
- Nov 2, 2018
- 03:31am PDT
- Departed FedEx location
- FEDEX SMARTPOST LOS ANGELES, CA 90022
- Nov 1, 2018
- 18:41pm PDT
- Arrived at FedEx location
- FEDEX SMARTPOST LOS ANGELES, CA 90022
- Nov 1, 2018
- 17:05pm PDT
- Picked up
- ARCADIA, CA 91006
- Nov 1, 2018
- 15:55pm PDT
- Tracking number provided
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Don B (11-10-2018)
#33
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My original, which I think was the original OEM pump, lasted 100k miles plus and it had the plastic impeller. Nothing wrong with it I just thought to replace it along with the thermostat while I was in there doing other work which was actually new coolant pipes etc for the extra SC radiator.
Everything is back together except for new antifreeze and finding a dropped socket.
Last edited by jackra_1; 11-10-2018 at 04:24 PM.
#34
#35
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Just to chime in late on this thread, if I recall correctly, the ACDelco water pump has a metal impeller. If I understand the literature correctly, the reason the OE impeller is plastic is to eliminate the effects of electrolysis and cavitation erosion that metal impellers are susceptible to when operating in OAT coolant. Probably not an issue in the near term, but in the long term it could be (think of eroded metal particles circulating through your cooling system).
I've installed several of the Airtex OE-style water pumps on X100s, X200s, X308s, X350s and a Range Rover, and have never had a problem. But I did once accidentally remove the screws that hold the two halves together on a car whose valley hose failed after I had already installed the new water pump, so I realized the torque of those two screws is critical to having a pump that doesn't leak. And now, thanks to John, we also know that the alignment of the two halves is critical. Thanks John!
Cheers,
Don
I've installed several of the Airtex OE-style water pumps on X100s, X200s, X308s, X350s and a Range Rover, and have never had a problem. But I did once accidentally remove the screws that hold the two halves together on a car whose valley hose failed after I had already installed the new water pump, so I realized the torque of those two screws is critical to having a pump that doesn't leak. And now, thanks to John, we also know that the alignment of the two halves is critical. Thanks John!
Cheers,
Don
Last edited by Don B; 12-08-2018 at 06:43 PM.
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