3L engine knock

[chocko]

I have a 2.8 litre 3L engine in my Hilux that has been fitted with a turbo off a 2.4LTE engine. The damn thing was running just fine then it developed a light knock that sounded a lot like excessive valve clearance as it was half engine speed. This has developed to the point where I can't get out of the driveway before this frightening knock bordering on misfire develops. When the engine is cold the noise is hard to pick up but as the engine warms up it becomes quite loud (though intermittent) rapidly progressing to the above mentioned frightening knock.
It is not a mechanical knock (big end or small end) as it comes and goes until the engine is warmed up and is half engine speed.
I have had the fuel pump overhauled and the injectors checked. I checked and adjusted the fuel pump timing and I have had the head off, valves and seats ground and valve clearances reset. Obviously the cam timing has been checked. Pistons and bores looked ok.
Blood hell where do I go next???

[Clanky]

Did you replace the cambelt and tensioners when you had the head off?

I believe on the 3L you need to renew the bolts that hold the tensioner on each belt change too as they have a habit of breaking in service.

You could also try to run the engine ( for a very short time) with the water pump and alternator and power steer / aircon belts off as a test

The front pulley / harmonic balancers - I have seen these delaminate ( the rubber segment in the middle of the pulley lets go in between the two sections.

[chocko]

Cam belt and tensioners have been changed.
Front pulley is fine.
Knock is very much at the top end of the engine.

[Clanky]

Is it injector pulse? Maybe one of your fuel lines is touching on something and amplifying the pulse?

Just throwing ideas at you.

[chocko]

Appreciate the ideas but this really is a scary sound. Wish I could record it and post it. After about 15 minutes running at a fast idle it gets so bad you have to turn the engine of f for fear that something will come out the side.
Let the engine cool and the whole process starts again!

[Clanky]

Oh, you say its scary, I thought it was just a little tapping sound like a valve.

Check your timing belt, right away. My bro's 3L broke a timing tensioner bolt, about 500kms after a belt change, and while it was still running it sounded pretty bad (like it had minced itself up internally.) and was much worse when hot.

[howesy]

when mine did that it was worn bearings allowing the rod and piston to stretch and knock when revved hot.
If you have run out of all other options and theories it
wouldnt hurt to pull the sump and replace the rod bearings. minimal cost and relatively easy. just have to use a ring spanner to undo the pickup before you can get the sump right off.

Just a thought

[chocko]

Cam belt and tensioner have been changed

[Clanky]

Good call by Howsey. Did you notice any unusual marks on the combustion face or pistons when you took the head off?

Does the noise vary (rattly) or is it static (regular) at the one engine speed?

Is it a fuel type knock?

Have you checked this gauze filter in th epump?
http://www.biofuelsforum.com/using_biod ... blems.html

[chocko]

Pretty sure it is not a bearing as the noise is high in the engine and half engine speed.

Didn't see anything unusual on the head or pistons. Head had a couple of leaky valves so had them ground and the seats cut just for laughs.

Fuel pump has been reconditioned as have the injectors

But it still sounds like a combustion knock

[BadMav]

Sounds like you're doing all the right things. Check your pump timing again and retard it a bit and see if it goes away. You may be a tooth out on the gears.

[howesy]

Pretty sure it is not a bearing as the noise is high in the engine and half engine speed.

Didn't see anything unusual on the head or pistons. Head had a couple of leaky valves so had them ground and the seats cut just for laughs.

Fuel pump has been reconditioned as have the injectors

But it still sounds like a combustion knock

The noise was high in my engine too. the rod stretch was just enough to gently touch the chambers and no marks were evident on mine either. Either way i reckon the bearing replacement even though a pain in the **** is good insurance with the turbo.
get that old screw driver or long bar happening. If the noise is up top it can only be injectors or pistons tapping. Maybe it only sounds up top but the bar listening device will narrow it for you and you will soon know if its injectors a sinister mechanical gremlin or something down lower. the only way to narrow it is to go all around the block with the bar and listen.

[chocko]

Well, I have resigned myself to pulling the engine and taking a look at the bottom end.

Keep you posted.

[Modified Toy]

loosen the injector pump and move it towards the block ad see if the knock gets worse.

[Gazrv6]

Head gasket thickness is very important on 3 & 5l engines as piston height varies, pre combustion chambers in head can come loose & they also have a bad habbit of no 4 big end letting go.

[matty savo]

a mate of mine had a hilux with the 3l motor and we did the timing belt and change all bolts all was good and then he developed this top and knock as well. I thought at first it was an injector or or something with the fuel but when we started to have a closer look we found that the crank pully on the timing belt had striped the key way and had moved the pulley putting the timing out. Might be worth a look.

[chocko]

Pulled the engine - #4 big end is toast. Crank is cracked and lost its hardness. Now for a "new" crankshaft................

[Clanky]

Sorry to hear mate.
Does it show any reason why this happened?
Bearing spun, crankshaft flaw, oil starvation?

cheers

[chocko]

Have had a yarn to a couple of blokes at work who have worked in automotive engine shops (we build industrial engines for a living) and know these engines pretty well. Apparently the L series engines are renowned for this failure. The Toyota bearing is aluminium which is makes it "soft". This is meant to protect the crank but driving the car hard over time causes the bearings to deform and come loose in the rod. It then turns and/or starts to break up. This is exactly what happened to mine; #4 had turned in the bore and a piece broke out of it - hence the knock. The other 3 showed the same signs of distress so weren't far behind it. Mains are in perfect condition as is the rest of the engine - the bores measure up with almost no wear as do the pistons, cam and bearings are spot on etc so it is not a lube thing. Just had the shit flogged out of it over time.
The fix according to these blokes is to fit a good quality tri-metal bearing; steel backed bronze with a lead overlay from ACL or someone similar. That is what I will be doing once I have tracked down another lumpy bit.

[howesy]

Yes it is common, and maybe the toyota bearings are a little soft as well but are you sure these guys really know the 2.8 motor?
It is well documented that the number 4 bearing issue is more oil related.
Sure use good quality bearings but it is extremely important in this motor to use thin oil and to change religiously without fail every 5000km with a filter. let it go over or scrimp on the $5 Z9 filters and you are asking for trouble.

[chocko]

Yeah they say the same about being religous with the oil changes. I have been since I have owned the car but that has only been 12 months and who knows what happened before I bought it........
Will build it as strong as I can, service it right and hopefully it will last. Have plans to replace it with a 3 fiddy anyway but have to keep it going until I have those ducks in a row.

[howesy]

Yeah they say the same about being religious with the oil changes. I have been since I have owned the car but that has only been 12 months and who knows what happened before I bought it........
Will build it as strong as I can, service it right and hopefully it will last. Have plans to replace it with a 3 fiddy anyway but have to keep it going until I have those ducks in a row.

cheers make sure you put the right head gasket on there is an A,B and C all different thicknesses
Done right and maintained you should have excellent reliability.
only other thing I can suggest for the 2.8 is that you will notice the head is high up in the engine bay and the heater hoses are at the highest point. I adapted a canister in line to take a water level warning sender and that way I got warning before the water level got down as far as the head. the head gasket is toast real easy if you spring a leak. I learnt the hard way and was saved twice during the life of the car after fitting the device.

[84luxy]

hey mate just reading on your post here, my hilux "91" done the same thing cracked crank would you know how much for another one or if the 2.4L would be compatible???, i had a 2LT bundera before this hilux and she was a dream, big regret getting rid of her but kids happen lol, so if you could help me out with the crank situation, if you got any tips from doing yours that would be great thanks emily

[oldmate]

In hiace buses it's common to load up with passengers and a trailer then the lazy driver doesn't downshift on hills. On hiluxes it's fitting big tires that loads up the engine. Either way it's the same problem. The engine doesn't get enough air, fuel doesn't combust properly. You get black smoke which causes over heating, but also oil contamination which leads to the bearing failures. The problem can be worse with after market turbos because there is no boost comensator on the fuel pump.