Strange noise after engine rebuild

blumr2 · June 26, 2024, 18:54

Hoping someone can point me in the right direction on how to investigate this. I have done a complete engine removal, strip down and clean. Main objective was replacing all the seals and new piston rings.

Put it all back together and it just about starts but has a loud clanking noise and no power. Took the engine out again and took the head off to check everything over but all looked fine.

No error codes on odb reader. I suspect a sensor got damaged in the build but no idea how to track down the one. All suggestions welcome!

https://youtube.com/shorts/zvuznKDj1MQ?si=yZCSEyMMkOU2QLev

Alex Knight · June 27, 2024, 09:26

What are your compression test results after the rebuild?

Joesson · June 27, 2024, 10:23

@blumr2
In days of old I would suggest that is "loose" tappets, not applicable with OHC but the cam clearances could be excessive, creating noise and loss of power.

Carolyn · June 27, 2024, 10:24

You need to inspect the bottom end too, I'm afraid.

Call the midlife! · June 27, 2024, 15:18

Did you make sure to reset the chain tensioner before starting up?

blumr2 · June 27, 2024, 22:43

Haven't got a compression test kit, but good idea I'll try and borrow one to check spec. Valves and their shims all went back in same order. I did grind in the seats so shims might be slightly out but can't see that would make this level of noise. Turns over smoothly with the plugs out. I replaced the chain tensioner, but yes that's where my thoughts are heading. Was wondering if a faulty sensor might cause the timing to be out, but with no dtc codes to go on maybe that's the wrong path. Looks like it's going to have to come out a third time.. Thanks all

Call the midlife! · June 27, 2024, 23:07

The actual timing is pretty much regulated by the chain and making sure everything is in the correct place when you put the chain back on in the first place.
The cam and crank sensors just tell the ECU where everything is at any given time, the fact that it's actually running would lead me more towards bottom end rather than valves etc. If the timing was that far out to be making that much noise you'd have bent the valves on first try and it wouldn't be running.
I asked about the chain tensioner because an engine can still run with a slack chain and it makes quite a noise bouncing around the chain guides before it starts taking chunks off the oil pump etc.

Alex Knight · June 28, 2024, 07:06

Quote from: blumr2 on June 27, 2024, 22:43Haven't got a compression test kit, but good idea I'll try and borrow one to check spec.

I'm genuinely astonished you rebuilt the engine and not once checked the compression (or leak down for that matter), given that your main objective was replacing piston rings.

A big oversight IMO.

Carolyn · June 28, 2024, 08:03

I say again - you really do need to get the sump off and make sure all is as it should be with the rod bearings.

blumr2 · June 29, 2024, 22:09

Absolutely bang on on Carolyn, unfortunately! Must have somehow missed torquing up that one bolt. Painful lesson. Oh well, live and learn. Anyone got an engine to sell?!

KRAMSNEHPETS · June 29, 2024, 23:29

Ouch....

Joesson · June 30, 2024, 07:24

"Ouch" indeed, very well observed @Carolyn, nothing else to "like" on this thread but another confirmation that "everyday is a school day on here" and we do have an excellent Tutor.

Carolyn · June 30, 2024, 07:58

Quote from: KRAMSNEHPETS on June 29, 2024, 23:29Ouch....

I take no pleasure in being right in instances like this. It's so easily done.

In the last few years I've taken to using a check list when rebuilding engines, as my short-term memory has decayed with advancing years!

At least you've got a refreshed cylinder head and new rings which can go in a used engine!!

J88TEO · June 30, 2024, 09:24

When I had my garage business, I marked the bolt heads as I torqued them.

Call the midlife! · June 30, 2024, 10:21

Quote from: J88TEO on June 30, 2024, 09:24When I had my garage business, I marked the bolt heads as I torqued them.

Yup. I'm fairly confident they should be to torque and then plus 90 degrees so need marking up for that reason also. Last thing I check before putting the oil pan on but it's all a good learning curve, especially when there's a steady supply of used engines at fairly low cost.

jvanzyl · July 6, 2024, 11:08

I have my old engine you can have for free. It was slightly burning oil, so can do with a refresh- otherwise working fine. I'm about an hour and half from you. Let me know.

blumr2 · July 7, 2024, 09:35

Wow that is really kind of you. I'll pm

blumr2 · December 28, 2024, 18:59

So, some months later and with the kind engine donation from @jvanzyl I've completed a second strip down and rebuild. I used the lower crankcase, a piston/con rod, and sump from the donor engine. Replaced the piston rings on the donated piston with ones from my prior engine as those were new. Now getting a different noise. Initially thought cam chain tensioner had maybe not released, but I've confirmed it has. Any suggestions on where to investigate next?!?

https://youtu.be/PIntQYQ8bn0?si=4AmhVsxJrrR6o4vh

Carolyn · December 28, 2024, 19:03

re-using ringswasn't the best idea as they conform to the bore when you run them in.

Can't tell anything from that vid. get yourself a stethoscope and pin the location down. They're cheap as chips.

blumr2 · December 28, 2024, 19:06

PS if anyone can use a free cylinder head (including camshafts), main block, 3 pistons, crankshaft, or oil pump pm me. Pick up, or pay postage.

blumr2 · December 29, 2024, 23:27

Rings only had 10 mins running time so hopefully ok. On a hunch, took the fan belt off - noise gone! Very relieved it's not an internal problem. Now just need to work out which pulley is misbehaving. Maybe stethoscope will help with that.