Bad engine knock

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trexified
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Joined: Sat Apr 14, 2018 9:40 pm

Bad engine knock

Post by trexified » Sat Apr 14, 2018 9:50 pm

I have a bad engine knock or rattle at start up when cold. It seems to be getting worse. Mechanic thinks its the timing chain slapping in the engine due to high miles (169000 mi). I noticed (think) its happening worse when the heater is on. Called the mecanic he says the only other thing it could be is a bad ac pump. What do you think? Its so bad i can hear it in my house at warmup 4 months ago it was whisper quite. When the engine warms up and finally goes away its whisper quiet again.


pwschuh
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Joined: Fri Nov 26, 2010 9:09 am
Location: Mid-Atlantic

Re: Bad engine knock

Post by pwschuh » Sun Apr 15, 2018 4:53 am

What have you tried to do to isolate the source of the noise? A 3ft length of rubber tubing used as a stethoscope can help narrow down specifically where the noise is coming from.
2008 TX Limited
Silver Birch Metallic/Black leather
WeatherTech floormats all rows
Bought used on 17 Nov 10 with 20,000 miles

trexified
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Joined: Sat Apr 14, 2018 9:40 pm

Re: Bad engine knock

Post by trexified » Sun Apr 15, 2018 8:22 am

My mechanic said it sounds like its coming from the valve train area. My ear says its the front right side.

spy1309
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Joined: Mon Jun 23, 2014 12:51 pm

Re: Bad engine knock

Post by spy1309 » Sun Apr 15, 2018 11:00 am

It might be a valve slap.....the engine has hydraulic valve lifters, if one is not working properly it will create a space between the valve and valve lifter and create a taping noise, when the oil is warm is thin enough to circulate.
Before any expensive repairs use some internal cleaner to clean all pasages of gunk and change oil with a good quality syntetic oil like Mobil One.
A timming chain slap would not go away when warm even do it has a hydraulic tensioner also controlled by oil pressure.

trexified
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Joined: Sat Apr 14, 2018 9:40 pm

Re: Bad engine knock

Post by trexified » Sun Apr 15, 2018 12:00 pm

What kind of internal cleaner? Is it an oil or gas additive? I apologize for being so ignorant.

spy1309
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Joined: Mon Jun 23, 2014 12:51 pm

Re: Bad engine knock

Post by spy1309 » Mon Apr 16, 2018 6:02 pm

Something like this.
https://www.walmart.ca/en/ip/motormedic ... 0077654272

Before you change the oil with the car parked and engine warmed up you dump this in the engine even ( don t worry about overfilling ) let the engine idle for 15 min , DO NOT REV THE ENGINE .....DO NOT DRIVEIT.....after 15 min dump the oil , change filter and refill with syntetic Mobil 1
https://www.walmart.ca/en/ip/mobil-1-5w ... 0016943647

You can add a can of Rislone to clean as you go
https://www.walmart.ca/en/ip/rislone-en ... 0194078531

If the issues is with cloged passages it should clear in 1000-2000 km

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