Hasi96

Hi guys, I drive a AP1 facelift Honda S2000 (we didn't get the AP2 in the UK). 2 years ago, the bottom end of the engine began to knock which meant a rebuild. The rebuild was completed and then after a month or so while blissfully in Vtec at high speed, i started to hear a ticking sound which progressively got louder. In terms of the work thats been done to diagnose I've listed below but the sound still persists:

Taken off the main drive belt.
Timing chain tensioner has been changed
Changed the cams and the valve train.
Set valve lash to 0.08 on the intake and 0.10 on the exhaust side and re-did it again.
Changed oil and oil filter twice with the second oil grade being 5w30.
Looked at the possible alternator bearing.
Looked at the AC pump and bearing.
Checked tensioner idler.
Checked Belt idler
Checked injectors.The sound is still persisting and myself and my mechanic and I are truly stumped.Does anyone have an idea of what this could be? Maybe it means checking and redoing the work although we have done this meticulously.

I cant post the video so hopefully the audio will suffice.

Any thoughts I can share with the builder would be much appreciated

Any thoughts would be much appreciated

Thanks

B serious

Rebuilding the bottom end of these engines typically doesn't work out.

Did your mechanic follow the FSM when rebuilding? Or did he do it based off prior experience with different cars?

Did he use factory parts?

And which part of the bottom end was knocking before the rebuild, and why?

Detailed history will help.

bruthaboost

If you checked all those things, it could be rod knock. Did you get a spec sheet with your rebuild? pics of bearing clearance (plastigauge)? There was a Donut vid of a LS crate motor they bought and did a tear down to show what you're getting and they incidentally found MULTIPLE engine destroying issues (bad bearing, missing wrist pin clip). So these things can happen.

Hasi96

In terms of the history of this car, it had a hard life before I bought it.

The first symptom was rod knock.
During the bottom end rebuild, the builder did the following:

"1) Built bottom end using a brand new looking crank
2) Piston and Rod from another engine which was in very good condition using new piston rings.
3) standard ACL big ends and mains bearings.
4) Torqued mains 22 ft/lb and 60°
5) Big ends 18ft/lb and 90°
6) New thrust washer bearing.
7) brand new oil pump.
8) New Timing chain, Oil pump, oil pump chian and new guides.
9) new set of oil squirters x 4.
10) reset inlet valves 0.8 on the inlet side and 0.10 exhaust side.
Honda OEM head gasket using new head bolts torqued 22ft/lb and 180°
Camshaft holders 16ft/lb.
Oil pan sealed using Hondabond.

First oil was mineral 20/50 ran engine idle for 30 minutes and drained it and added a second 20/50 for bedding in and then changed to 10/40 as recommended by Ramos since it's a high milage.
Then changed oil and oil filter using a larger recommended OEM oil filter for the s2000 and 5/40 engine oil as according to data.
Changed oil and oil filter again using 5/30 and a regular Hamp oil filter. This seemed to run it quiter.
The crank has been inspected twice and zero scoring - Infancy, it's like a mirror chrome.
All four rod bearings are good and all journals are mirror chrome.
All four pistons were sound with now scoring on the side skirts.
All for liners were good with no scoring.
Piston to wall was measured and was within spec for n/a engine reading just shy of 0.6 piston to wall.
When I fit new pistons in all other Honda build I keep the piston to wall clearance 0.3 for turbo and 0.5 for n/a."

So the builder is convicned its not the build and I don't suspect so either.
This noise occurred afterwords upon hard driving by myself. Then replaced the head and still the noise remained

Builders History:
Building Fords, Rotary, Lexus V8's, a few Audi tt's, Toyota Corolla, Yaris, Honda's, CBR's, Jet Ski's, Chopers, Four Barrell Holley Carbs etc, etc.

Car Analogy

To achieve high rpm survival, manufacturers like Ferrari spend big money on precision machining to achieve precise clearances required.

Honda did it cleverly on budget. They just made different size bearings, different size pistons. The motors were built by hand, and builder would mic up crank and block select best bearing size for each main position. Then do same for rod bearings. Same for pistons.

So they'd use standard machining tolerences, but achieve Ferrari precision by just using correct bearing size.

When rebuilding, if crank wasn't machined and its original crank for the block, original rods, you can just reuse the sizes for each used by factory, which were are stamped into these components when engine was built.

Otherwise you have to measure everything yourself, then choose the correct bearings. If you just randomly select these parts before you even tear engine apart to know what sizes factory used, your clearances are virtually guaranteed to be off. Engine won't last long at upper rpms.

Now, if you never rev the thing past, say, 6.5k rpm, its not going to be much of a problem. Standard tolerances, standard redline. But to survive our redline, precision required.

For some reason your builder use aftermarket bearings, which don't come in these sizes. So your clearances were almost surely off. Your motor never had a chance.

Interestingly, these aftermarket bearings do come in .030 over, etc. Oversize bearings traditionally used when crank is damaged. So they machine it smaller, use bearings to make up the difference. Except you can't do that with our cranks, because you machine past the hardened layer, and no seams to have figured out a rehardening protocol that brings success. So these oversize bearings are useless.

People constantly be trying to upgrade these motors when the factory parts almost always work better.

BTW, this is what people were talking about when they asked if your builder just did what they've always done with other motors. Just because that always worked fantastic on others motors doesn't mean it works on ours. In this case its cost you a motor.

The said part is now your previously perfect crank is probably damaged now. Next the builder is going to suggest machining it down. Because that always works on other motors. See a pattern?

The next rebuild will last even shorter life.

Prediction. When you try and mention this to your builder, he's going to say people on internet don't know what they're talking about. He'll say he's been building successful motors for x decades. How many racers used his stuff, yadda yadda.

But who has a rebuilt motor that has only lasted a few k miles?

Hasi96

From the builder:

"I used plastigauge to check for clearances for the Mains AND Big ends and all were as tight as within 0.2.
But it's not the bottom end. It's the top. The noise is on the top.

Furthermore, when I opened up the engine it already had +02 oversize bearings and there is no next size up to select bearings and is the reason why a new crank was needed.
+02 oversize bearings means that the engine was opened up twice before and mine is the third time.
Again, there is nothing wrong with your engine, it's the top. When we started it the other day, water was coming out of the exhaust, a sign of a good engine"

Indeed, when he took the engine apart, there were hammer marks on the underside, which he showed me...but he maintains the bottom end is not the issue and the its the top end. He maintains that if it were his build, an engine as precise as the s2000 would have exploded within the first 10 miles.

I also do not think its engine related for that reason - but again im open to any possible diagnosis

engifineer

Water coming out of the exhaust right after startup is simply condensation from when the exhaust cooled after the last drive. Has nothing to do with how good your engine is.

bruthaboost

Additionally, H2O is a byproduct of combustion. We usually don't see it because once the engine and exhaust is at operating temperature, it vaporizes the water to steam so we don't see it.

windhund116

I don't think I've ever heard anyone say that or read in any owner's manual --- re: "startup exhaust steam is the sign of a good engine." I've seen cars with blown head gaskets pump like a steam engine. But that's a bad thing.

It's an odd thing for that mechanic to say.

engifineer

Yeah for sure, if steam and especially sweet smelling, it is a bad thing!