5K Engine Noise

[Viterbo]

Crank and bearings are perfect, nothing spun, no marks... Piston pins apparently have no gap...

Haven't checked side gap on the piston heads yet.

Chain doesn't seem to have much gap to cause a knock like this. No marks on the timing cover of the chain hitting it.

I'm running out of options for the problem...

Edited May 8, 2016 by Viterbo

[Banjo]

It's going to be very frustrating if you put it all back together again, fire it up & the noise is still there. Real need now, is to find out whether the noise is dynamic or static. That means, does the noise only occur as a function of detonation, or is it something mechanical, unrelated to the engine running.

 

I'd put the sump back on, sit the engine in a couple of old tyres, (assuming it is out of the car), put some oils in it, & turn the engine over using a big electric drill connected to the crankshaft pulley.

 

That should be enough revs to create the noise if it is mechanical.

 

Let's know how you go.

 

P.S. Did you use the stethoscope test ? Did that show up anything ?

 

Cheers Banjo

[coln72]

I had a weird engine noise with my 5k. Changed speed with revs, disappeared when number 3 plug lead was removed. Assumed it had cracked a piston. Pulled it out, sent it off and nothing found.

 

Only issue we found was that the inlet manifold was broken on number 3 inlet runner when the manifold was pulled off. Welded up, no more issues

[Clapped out]

+1 with corollart, lifter/cam/rocker gear.

[Viterbo]

Banjo the stethoscope test pointed to the rear of the engine around the piston area.

 

I was told to make the following test:

Do the process of tunning valve gaps and check for gap on the pushrods by moving them up and down by hand and found this: all pushrods are rock solid (no movement) except 2. From front to back, pushrods 4 and 6 (cylinder 2 and 3) have a gap of 1mm or so and we can hear a "tac tac". Does this mean anything?

[Banjo]

Think you are heading in the right direction. It is looking like it might just be tappet noise, introduced by maybe a faulty hydraulic valve lifter or two.

 

Does your 5K have hydraulic lifters ? There were some 5Ks apparently fitted as standard with adjustable tappets. I ask that, because you mentioned "tuning valve gaps", which can only been carried out on adjustable tappets. Has this engine ever been converted to solid push rod lifters ? If it has hydraulic lifters, it is quite common for 5Ks with lots of klms, to have a noisy tappet, as a result of a hydraulic lifter leaking. This usually happens at start up, but usually disappears after the oil pressure builds up quickly. However, if the noise persists, it is quite often an indictation of a faulty or very worn lifter.

 

Have you removed all the lifters, (one at a time, or number them 1-8) and dissembled cleaned & checked that no internal springs have broken ? If you are going to clean them, here is a good video that will assist. It's not for a 5K, but the technique is the same.

 

 

Here is link to a good wikipedia description of how hydraulic lifters works.

 

https://en.wikipedia.org/wiki/Hydraulic_tappet

 

The valve lifters are right next to the cylinder in the block, which would line up with your comments about where the noise appeared to be coming from. A "point tip" stethoscope can detect each valve lifter quite easily, as the valve lifter is located very close to the outside of the block, and that area is easily accessible on the 5K, as a result of it's slant installation.

 

Cheers Banjo

Edited May 9, 2016 by Banjo

[Viterbo]

I mentioned tuning valve gaps to refer to the process. Cross valves in cylinder 1 to tune cylinder 4. But instead of tuning the gap, I tried to find a pushrod working differently from others.

I'm using standard hydraulic lifters.

[Banjo]

Have you tried this Nulon product ?

 

http://www.nulon.com.au/products/Engine_Treatments/Lifter-Free_and_Tune-Up

[Viterbo]

Nop, just petrol and oil hehe

I'm gonna take the lifters out and check them.

 

A couple of photos:

 

 

[Banjo]

How many klms have you done since the engine rebuild ? The initial wear markings on the new main & conrod slipper bearings look a bit uneven.

 

Have you ever measured the engine oil press with a good guage after the rebuild ?

[Viterbo]

I've done a bit less than 200kms but I wasted around 30L of fuel in addition to those kms with the car standing just testing carbs (I got carb issues and had to replace it).

I think the car worked an amount of time to do more than 500kms.

Haven't measured since the rebuild

[Viterbo]

Without taking out the head yet 3 issues were found:

3 lifters are defective, camshaft bearings look like they are the factory ones and the chain guide (not the tensioner) has a lot of wear...

I disassembled one of the damaged lifters and when I assembled it back it became "good" without the gap it was showing before. Can it be used or it will get faulty again?

[Banjo]

Not sure what you mean, when you describe the lifters as defective & damaged. If they are that bad, then you replace then, or go to solid lifters, and change all your rocker gear.

 

If you just mean that three (3) don't work, then you may be able to resolve the issue by carefully keeping each lifter & it's internal components together & associated with the position it came from. If you then meticulously clean them, and remove any oil stain "varnish" & reassemble & fill with oil, as described in the video link in my earlier response, you may well be able to overcome the problem.

 

If you read the detailed description of how lifters work, then you will appreciate a lot of things all have to be just right for the lifter to work. If you are going to replace the hydraulic lifters with new ones, it will be expensive & should really involve the cam & probably it's bearings also. Could be a very costly operation, all up. That's when the solid lifter conversion looks a lot more attractive.

 

After saying that, I've had two (2) off 5K motors & never had a lifter problem with any of them. Most hydraulic lifters work very well throughout the life of the motor, but on very old motors, with unknown history, and lots of klms, and build up of gunk & oil varnish, it's more than likely that's when hydraulic lifter issues will arise, with age.

 

If you've got the time, & the possibility of having to remove the engine again, if it does not work, I'd just clean meticulously, refill with oil & give it a try.

 

At least, I think you've solve the issue of the source of your noise. It's now just a matter of how you want to solve it.

 

Cheers Banjo

Edited May 12, 2016 by Banjo

[altezzaclub]

The initial wear markings on the new main & conrod slipper bearings look a bit uneven.

 

I wondered if the crank was slightly bent, looking at the wear to one side of the mains at the front, the other side of the mains at the rear. Not enough to worry about.

 

..and I reckon oil sludge and varnish will be the problem in the lifters. Strip & clean them all..Carb cleaner or paint stripper unless there are rubber O-rings involved.

[Clapped out]

I'd personally replace all the lifters and cam bearings with new ones, at least its another tick off the list and don't have to worry about it for the life of the engine.

 

Cheers!