Engine Knocking sound RB30

[BLISTK]

Hey people,

My Brother got a R31 Skyline from a friend for free. I took it for a spin and between about 1.5k to 3.5k rpm there is a knoking sound like metal on metal. I thoung that it might be lifters but when at idle there is no noise and same during cuise at 2k rpm.

I havent checked the timeing so i dont know if it could be detonation. It sound like it.

Also there seems to be a bit of hesitation when i accelarate.

Anyways any advice welcome. We are going to muck arround with it this weekend.

[mmcleo11]

Sounds like it could be big end bearings, which is probably why it was a free car May also be the injectors squaling, which is common but does not cause any mechanical problems. Lifters are also a common problem.

RB30 motors are pretty cheap as they were also used in the VL commodore so when the existing motor goes bang, just put in a new motor

The RB30 motors are near indestructable though. I would recommend a 2.5" exhaust and a set of extractors if you want a bit more fun from the 3L motor though

[BLISTK]

Originally Posted by mmcleo11

Sounds like it could be big end bearings, which is probably why it was a free car May also be the injectors squaling, which is common but does not cause any mechanical problems. Lifters are also a common problem.

Yeah but if it is the big end bearings would the noise be present at idle? I think that if its something mechanical it would be present through out the rev range.

Anyhow i will have a look at it in the morning to see what i can make of it.

And your right RB30 are very good engines i Have a VL T BT1 and this thing just puts out power like no tommorow. I has 275Kw @dweels anyways have a good weekend.

[BLISTK]

Ok,

Well now that i have spoken to my brothers frind that gave him the car I found that the Knocking started right after the engine overheated. But he told me the engine didnt sieze he just noticed that the water temp was high and pulled over. Filled it and drove home and then is when the knock started.

So from what i can gether to me its sounds like its the Rod bearingst. There loudest at about 2k to 2.5k. I pulled to top cover off and the valve train seems ok and the Spark Plugs look very healty no excessive corroding or carbon buildup. All well if am in the moode might take the oil pan off and a have a look up skirt

Does anyone here have a RB30 Manual in PDF of something??

What do you think??

[mmcleo11]

Rod big end bearings are most noticeable between 2000rpm and about 3000rpm. I heard quite a few nasty rattles like that before...

You can use a screwdriver with a long handle and place the tip up against the block. The handle rests up against your ear and it acts as a good way of hearing the rattle in the block. If it is rattling, then the crank will be damaged and a secondhand motor with a 6 month/10,000km warranty is normally around $500.

Getting the sump off in a R31 is a right royal pain. Have to unbolt the engine mounts from the cross member and jack the motor up to get room to get the sump off.

[BLISTK]

Originally Posted by mmcleo11

secondhand motor with a 6 month/10,000km warranty is normally around $500.

Where can you get motors like that??

Option 2 would be to rebuild it which might be fun but then again costly if we stuff something up, but it would be a lerning curve.

Hmm option 3. Take it to the paddic and thrash the shit out it till she goes

Option 3 strting to sound good

[DanGee711]

nah mate!its sounds like your hydraulic lifters have give up the ghost,big end bgs knock on initial acceleration!rev quickly and if it bangs its big ends!
tapping at low revs is valve train!