turbo whistle ???
- Chris James
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Chris & Shirley 096
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- Holmz
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A leak from the turbo to the engine.
Or a leak in the zorst, between the engine an turbo.
Maybe stuff a potato in zorst and see if it makes some exhaust appear somewhere ?
I would think a "vacuum type" of line blown off the intake is also likely.
You probably need an assistant maybe with a stethoscope type of listening tube to Yoda around...
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- mort
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What you describe it sounds more like your turbo and if so then it is the compressor or turbine wheel scraping on the side of the housing and for that to happen it will be that the bearing is worn. To check take off either the air inlet or dump pipe and see/feel if there is any play either sideways or in and out and that will confirm.
I know you say it was rebuilt so assuming it was done right what is forgotten or not known is to pre oil before start or at least start and idle for some time before reving to allow the oil to lube the bearings first before loading.
The turbo is under load when it is boosting and that is really only when you are accelerating driving under load.
Martyn
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- mort
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Been thinking a bit more and if it is a distinct whistle and not a screech then it could be just the compressed air leaking from your fittings between the turbo and your intake manifold so if you have an intercooler then check all the fittings and if not then you only have the flexible connection between turbo and manifold.
Martyn
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- Peter and Sandra OKA 374
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OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Holmz
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- Peter and Sandra OKA 374
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By the time I'd stopped the truck and opened the engine hatch it sunk in that the engine was still idling and apart from a loud sucking noise it seemed fine, then realised that the hose between turbo and intake had blown off with the boost pressure.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 1100w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Ralley
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If you do check for play in the bearing remember that it will have a little bit of clearance.
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- Holmz
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Or...
In a roller bearing it results in more of a vibratory force.
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- mort
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Yes I have had a connection on the pressure side blow on different engines and after you settle down you wonder what has just blown up but the up side is that you know that your heart can still beat pretty fast.
Martyn
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- mort
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Yes you are right the turbo will spin anywhere up to and beyond 150,000 RPM so an unbalanced turbo will damage the bearings very quickly then the wheels.
I would think that what is ment is the balance between turbine and compressor wheels...maybe.
Martyn
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- mort
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A diesel turbo will whistle and in fact most people who want a good performing and tuned engine will want the whistle where a petrol engine turbo will rearly whistle this is due to the design of the turbo and the difference of the RPM as a diesel will rev lower and achieve peak power well before a petrol engine.
A turbo will suck in the air compress it and push it out this process creates a vortex which gives a whistle.
Chris may have a turbo that is now working fine and for the first time he is hearing a whistle and thinks something is wrong when in fact all is ok so until we get more feedback we dont really know and are only guessing.
Martyn
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- Chris James
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To move it I have to make legs etc to lift it a little to move the truck forward a couple of feet so that is my next move,I will report my findings when I have some. Thanks again, Chris.
Chris & Shirley 096
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- Chris James
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At that point of the exercise I had a relapse of a fever that I have from time to time, similar to Q fever and just as bad so have been left with the will to continue but not much energy to do so.
Will report back when I know more, Chris.
Chris & Shirley 096
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- Peter Davis
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Peter
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- Holmz
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- mort
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Yes it does seem like a primitive joint but it is ok. If it wasn't a really sloppy fit when installed then it may be that you havn't fully fitted as there is a sholder inside the dump pipe which should fit right up to the flange of the turbo and sitting square before fitting the bracket that bolts to the back of the dump pipe and block. I have found that sometimes it has been tight and I need to use a rubber mallet or if too tight because dump pipe out of round then used a die grinder to take a fraction off.
The other cause could be that you have a baffled muffler that is partially blocked by soot and carbon causing too much back pressure. You could remove your muffler then see if you get the whistle which would be easier to eliminate that first before your dump pipe and if it is then replace your muffler with free flow muffler or just straight pipe ie no muffler.
Martyn
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- alanj
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Did you manage to fix the whistling problem? Mine also has a loud whistle that comes in around 1000rpm and fades out around 1700. I thought it may be the turbo but I'm not sure.
I'm interested in seeing how you progress.
Alan.
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- alanj
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I thought I would post a bit of progress with the whistling sound.
After some advice from a learned Oka owner, I dismantled the turbo hoses and pipes to look for the problem.
Interestingly, the cast iron dump pipe off the turbo is cracked up near where it connects to the turbo exhaust outlet. I was surprised because it is a big heavy chunk of cast iron.
Has anyone else had a similar issue?
Would anyone out there happen to have one sitting around gathering dust who would love to see it go to a good home?
Alan.
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- Holmz
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A friend has some nickel-bronze, or nickel-?? Sticks that cost $1200 for a pack, and I could get a stick or two off him.
I recall he used them for building up a gear tooth.
There is also a mob in the US that does some special sticks for cast iron.
The other alternative, which is probably a good idea, is to just remove the pipe, and use it as the template for a pipe welded out of some stainless and mandrel bends.
304,308 are commonly used in heavier gauges (2 to 3-mm) for this type of work.
316 is better, and 321 is the king and allows for thinner gauges, and it used for most aircraft.
The next step up is inconnel 625 and similar nickel alloys, which is more of what F1 and other weight critical motorsports and aircraft would lean towards... often in 0.6-mm thickness!
For the OKA a think 304 is likely ideal, and maybe some Vibrant V-Bands (TM) as connectors...
Then save the drawing as the next bloke will need one too at some point!
Most of the heat is between the engine and turbo, so some ceramic coating on the manifold, or heat shielding asbestos looking tape wrap with stainless zip ties can keep some of the heat inside the pipe. If the parts are out, then it is a better time to do that.
Most pipes do not like more heat, and the thicker gauges, or alloys better with heat characteristics are used.
Keep some heat out of the engine bay might make some sense if you are in there anyhow?
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