Turbo seal

Hi folks,

Is there any way of checking the seals on a turbo charger before running
my rebuilt engine ? I wondered about measuring pressure loss by
sealing one end and blowing compressed air in, sealing it and watching
the pressure decay, or is a certain leak normal ? Does replacing the
seals require rebalancing afterwards ?

Steve

On or around Sat, 17 Dec 2005 11:40:56 +0000, Steve
<[email protected]> enlightened us thusly:

>Hi folks,
>
>Is there any way of checking the seals on a turbo charger before running
> my rebuilt engine ? I wondered about measuring pressure loss by
>sealing one end and blowing compressed air in, sealing it and watching
>the pressure decay, or is a certain leak normal ? Does replacing the
>seals require rebalancing afterwards ?

are they likely to be a problem?
--
Austin Shackles. www.ddol-las.net my opinions are just that
"Pereant qui ante nos nostra dixerunt"
(confound the men who have made our remarks before us.)
Aelius Donatus (4th Cent.) [St. Jerome, Commentary on Ecclesiastes]

Austin Shackles wrote:
> On or around Sat, 17 Dec 2005 11:40:56 +0000, Steve
> <[email protected]> enlightened us thusly:
>
>> Hi folks,
>>
>> Is there any way of checking the seals on a turbo charger before running
>> my rebuilt engine ? I wondered about measuring pressure loss by
>> sealing one end and blowing compressed air in, sealing it and watching
>> the pressure decay, or is a certain leak normal ? Does replacing the
>> seals require rebalancing afterwards ?
>
> are they likely to be a problem?

The air outlet (into the engine) looks wet with oil. And something
wrecked this engine (before the rebuild).

Steve

Austin Shackles wrote:
> On or around Sat, 17 Dec 2005 11:40:56 +0000, Steve
> <[email protected]> enlightened us thusly:
>
>
>>Hi folks,
>>
>>Is there any way of checking the seals on a turbo charger before running
>> my rebuilt engine ? I wondered about measuring pressure loss by
>>sealing one end and blowing compressed air in, sealing it and watching
>>the pressure decay, or is a certain leak normal ? Does replacing the
>>seals require rebalancing afterwards ?
>
>
> are they likely to be a problem?

Turbo seals are not 'seals' in the commonly understood manner. They will
leak air.

As Austin suggests thay are not likely to be a problem.

The most important thing is to make sure that there is oil at the turbo
oil inlet at start up. Prime the turbo by injecting oil after
disconnecting the oil feed hose. Then prime the entire engine before
permitting firing to occur.

There was another thread entitled 'turbo priming' here last week.

Dougal wrote:

> There was another thread entitled 'turbo priming' here last week.

That was mine too, before I found the oil in the air outlet side. Now I
wonder if the engine ran away at some point.

Steve

Steve wrote:

> Austin Shackles wrote:
>
>> On or around Sat, 17 Dec 2005 11:40:56 +0000, Steve
>> <[email protected]> enlightened us thusly:
>>
>>> Hi folks,
>>>
>>> Is there any way of checking the seals on a turbo charger before
>>> running my rebuilt engine ? I wondered about measuring pressure loss
>>> by sealing one end and blowing compressed air in, sealing it and
>>> watching the pressure decay, or is a certain leak normal ? Does
>>> replacing the seals require rebalancing afterwards ?
>>
>>
>> are they likely to be a problem?
>
>
> The air outlet (into the engine) looks wet with oil. And something
> wrecked this engine (before the rebuild).
>
> Steve

There's wet and wet!

Do you know the actual history of the engine before the rebuild? What
sort of damage was present.

There's probably not much you can do to check the turbo without
dismantling it (which is not usually a good thing). Check for any damage
to compressor and turbine blades. Is there any evidence of either wheel
contacting the casing? Check end float and radial play of the rotating
assembly. Any noises when rotated by hand? Oil in the compressor outlet
can be the result of excessive crankcase pressure (turbo oil cannot
drain back to sump as intended), restricted turbo oil drain (draining
problem again), high vacuum at compressor inlet (restricted air cleaner?
- oil is sucked out).

If the oil is only on the air side of the turbo it's probably a good sign.

Dougal wrote:


>
> There's wet and wet!
Thats the issue - I haven't enough experience in this area to know what
is happening.


>
> Do you know the actual history of the engine before the rebuild? What
> sort of damage was present.
>

No history, 'twas "running", but rough as a bear's arse - The main
damage was knackered pistons, cylinder scoring in 2 and 3 - the rings
were intact, but the ring grooves from the top and second ring were
broken vertically to the piston crown. The crowns were unburnt. The
valve guides were knackered on 2 and 3, and barely on spec on 1 and 4.

The head was warped slighly.

The exhaust valve tappet adjuster on 2 was bent.

Just about every seal face had been gashed up with black silicone
sealant, and the water pump pulley plate was warped.

Project pictures soon.

> There's probably not much you can do to check the turbo without
> dismantling it (which is not usually a good thing).
You don't mean dismounting the turbines though, do you ?

>Check end float and radial play of the rotating
> assembly.
I can measure that to a 0.0001 of an inch if necessary, but have you any
ideas what is "OK" and what is "buggered" ?


> Any noises when rotated by hand? Oil in the compressor outlet
> can be the result of excessive crankcase pressure (turbo oil cannot
> drain back to sump as intended), restricted turbo oil drain (draining
> problem again), high vacuum at compressor inlet (restricted air cleaner?
> - oil is sucked out).

Arghhh. There were no blocked galleries when we checked them, but then
the block itself was being pressurised by the knackered pots.

> If the oil is only on the air side of the turbo it's probably a good sign.

Yes, theres none on the exhaust side. Its very clean in there.

Thanks for your comments Dougal. I am just being paranoid, but then
there is about 500 quid worth of rebore, reworked head, reworked cam
bearings, and a eyewatering amount of parts from Richard at BeamEnds in
it, I don't want to fsck it up on the first run !
Cheers

Steve

if you are realy not sure then just start the engine after normal
precautions then have a fire extinguisher handy, if the engine starts to
runaway then just dump the contents of the extinguisher into the inlet
manifold. But to be honest if it were going to leak that much I suspect it
would be only too visible before fitting.
"Steve" <[email protected]> wrote in message
news:[email protected]...
> Dougal wrote:
>
>> There was another thread entitled 'turbo priming' here last week.
>
> That was mine too, before I found the oil in the air outlet side. Now I
> wonder if the engine ran away at some point.
>
> Steve

"Steve" <[email protected]> wrote in message
news:[email protected]...
> Dougal wrote:
>
>> There was another thread entitled 'turbo priming' here last week.
>
> That was mine too, before I found the oil in the air outlet side. Now I
> wonder if the engine ran away at some point.
>
> Steve

It is possible for the oil seals to fail and in a simple turbo engine this
would be unremarkable but in an intercooled engine there is the possibility
of the oil filling the intercooler up, depending on entry and exit
positions. In such a case there would be little warning until a critical
point when the oil starts to be pulled over into the inlet manifold with
critical consequences.
I would get an exchange turbo and would remove the intercooler and wash it
out with a special cleaner. Genkleen was the name of a solvent cleaner
available for this purpose at one time I think.
It should be possible for you to replace seals in a turbo yourself but
getting the parts might be difficult. If the engine is a high miler then a
repair or exchange by one of the many specialists would be the best bet. An
exchange will probably set you back £400+ though.

Huw

if you are realy not sure then just start the engine after normal
precautions then have a fire extinguisher handy, if the engine starts to
runaway then just dump the contents of the extinguisher into the inlet
manifold. But to be honest if it were going to leak that much I suspect it
would be only too visible before fitting.
"Steve" <[email protected]> wrote in message
news:[email protected]...
> Dougal wrote:
>
>> There was another thread entitled 'turbo priming' here last week.
>
> That was mine too, before I found the oil in the air outlet side. Now I
> wonder if the engine ran away at some point.
>
> Steve