All of a sudden she started making this loud knocking/tapping

Post by **nickelghandi** » 06 Feb 2018, 10:21

I had the same thing happen with my 98 S70 GLT.

Check all vacuum lines. Particularly the one I believe is for the evap system. It connects to a check valve and I think a T-fitting. I didn't pay much attention because when it happened all I cared about was that it might be the source of the noise for me and it was!

I recently replaced my radiator hoses and knocked the crusty hose loose. When I started up after, it was fine, but I took it for a little drive to get the air out of the cooling system and it started making that sound. I was terrified I had knocked a sensor loose and ruined something internally somehow. I pulled off the road and checked everything near where the lower rad hose was. I found that the vacuum hose had come loose. I must have knocked it somewhat loose during the hose replacement and then it just fell off with vacuum or positive pressure during driving. I wasn't going fast or accelerating hard when it happened either. The hose is really rotten and I plan to replace it soon. I am sure if the hose is bad enough it can come off on its own.

I will post a picture of the hose later today when I am home in case I am wrong on which one it is. It is a larger hose and that air leak has exactly that sound and it goes up and down with the RPMs.

The hose is located near or under the intake tube to the front of the engine bay. It is close to the upper intercooler hose as too. Again I don't remember exactly, but you will know it when you find it.

I am hoping it is this easy of a fix for you. Good luck.

shadetree_v70 · Post by **shadetree_v70** » 07 Feb 2018, 03:38

Thanks for the suggestion

Post by **sleddriver** » 08 Feb 2018, 11:51

My guess is a stuck lifter as it sounds 'metalic'. Metal hitting metal. Perhaps it was oil-starved due to a small oil passage clogging over time & miles. Not sure if any 'mechanic-in-a-can' will fix this. I've used BG109 engine flush a few times for a good internal 'wash' before changing oil. You may have to run it with 109 for 10 - 15 min., shut off the engine, close the hood and wait for 30 min., then run it again for 10 -15 min. and repeat several times. Don't drive it with 109 in there as the oil viscosity will be close to 0.

You may have other lifters heading the same direction, they just haven't started making noise yet. I only use synthetic oil: M1 10w-30 HM. Down here it's brutually hot & humid. A bit different than Charleston.

Post by **mrbrian200** » 08 Feb 2018, 17:48

Read the comments to the video on youtube website. Says sump seals were bad, no pressure to top end. New o-rings, noise gone. Watched quite a few videos until I found one that sounded *exactly* like yours.

Ahem, don't drive it until it's fixed.

https://www.youtube.com/watch?v=-kCj3F5jAUI

shadetree_v70 · Post by **shadetree_v70** » 09 Feb 2018, 09:50

I will be dropping the oil pan tomorrow to install the sump o ring kit, and I agree with the conclusion arrived at by several of you is that I've lost oil pressure and its just not feeding enough to the top end. Like that last clip, the oil isn't splashing enough out of the fill hole to indicate adequate pressure, and the noise its making doesn't immediately point to crank bearings. Hopefully this takes care of it.

I have some anaerobic sealant left over from a headgasket job i did 2 years ago, maybe 1/3 of the tube remains. Is that enough to form a new seal, and is that stuff affected by temperature? it's been sitting in my toolbox in the garage through the hottest (100+) and coldest (20s) days in Charleston, didn't know if it breaks down or gets funky when it's not in its anaerobic state.

Post by **abscate** » 09 Feb 2018, 10:24

Throw the sealer out and buy a new tube. Compare cost of sealer with labor to redo cover.

Search threads for guidance on amount needed...donate extra to pay forward karma

Post by **FlyingVolvo** » 09 Feb 2018, 10:41

ONLY use the Volvo sealant for that job. Volvo Gasket Sealant PN: 1161 059–9

Here's my thread on the oil pan job: viewtopic.php?t=31236

I used a mini foam roller to get it all on nice and even.

shadetree_v70 · Post by **shadetree_v70** » 09 Feb 2018, 11:00

abscate wrote: ↑09 Feb 2018, 10:24 Throw the sealer out and buy a new tube. Compare cost of sealer with labor to redo cover.

Search threads for guidance on amount needed...donate extra to pay forward karma

New sealer it is. As for Karma, we will see how things go lol.

One last question before I update on the repair: Is there a good way to see if crank bearings are good? I assume Ill be looking at the condition of the crank surface. Does it make sense to change them while it's torn apart given the mileage?

Post by **mrbrian200** » 09 Feb 2018, 12:10

shadetree_v70 wrote: ↑09 Feb 2018, 11:00
One last question before I update on the repair: Is there a good way to see if crank bearings are good? I assume Ill be looking at the condition of the crank surface. Does it make sense to change them while it's torn apart given the mileage?

Plastigage

I don't know what engine he's working on, you would need to look up the allowable clearance and proper torque spec for your engine.

shadetree_v70 · Post by **shadetree_v70** » 18 Feb 2018, 14:54

Dropped the pan, cleaned it all out, removed sump tube and screen, replaced O rings, cleaned the square PCV hole (was completely clogged), put it all back together, same sound. GRRRRR now what? It seems that oil pressure is still low, when I take off the oil cap the oil doesn’t splash out, it just kind of flings around from the cams. Oil light is not lit by the way.

All of a sudden she started making this loud knocking/tapping

Re: All of a sudden she started making this loud knocking/tapping