advice needed - weird temps

[tony roberts]

Hi
I have a newly rebuilt 0300-D.
It is running hot - at OAT 93F, 2 cylinders are exceeding 400F on
climbout and oil exceeds 200F.

(BUT EGT's are perfect - less than 45F spread on my EI Monitor)

On runup, no rise in RPM prior to drop on leaning!

All baffling is brand new and installed correctly.
I have been told that I need to increase fuel flow to improve cooling.
I don't like going to my A&E without knowing what needs doing, why and
how (it's a long story :)

So - how do I increase fuelflow on my engine?

Also - Cylinder 5 is too cool - running less than 300F CHT - which means
it isn't scavenging lead - a recipe for sticking valves. I have been
told it's because it is out front - but so is cyl 6 and that is one of
the hottest.

I am running TCP in the 100ll and Avblend in the oil - the engine is
smooth as silk and has 30 hours on it.

All suggestions highly appreciated.

TIA

Tony

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

[Bob Noel]

In article <nospam-97F34F.08333904092005@shawnews>,
tony roberts > wrote:

> Hi
> I have a newly rebuilt 0300-D.
> It is running hot - at OAT 93F, 2 cylinders are exceeding 400F on
> climbout and oil exceeds 200F.
[snip]
> All suggestions highly appreciated.

recheck baffling

check oil temp probe for accuracy

check CHT probes for accuracy (all of them)

Is 400F a temp redline or isn't it 500F? For my Lycoming O-320,
the manual discusses having cruise CHT temps at or below 400F,
with 500F redline.

btw - EGT spreads aren't meaningful (the EI engine monitor
manual should have some discussion of this).

Have you talked to anyone at the shop that rebuilt the engine?

--
Bob Noel
no one likes an educated mule

[Jon Kraus]

I am not an A & P (nor have I played one on TV) but it sounds like a
normal occurance in a newly rebuilt engine. I think that once thigs
break in a little more (and loosen up) you'll see a drop in temps along
with oil consumption. At least this is according to the rebuild books I
have read.

That being said, If I just spent up to 20 AMU's for a rebuild I
certainly wouldn't hesitate to ask the rebuild shop questions. Good luck!!

Jon Kraus
'79 Mooney 201
4443H @ TYQ

tony roberts wrote:

> Hi
> I have a newly rebuilt 0300-D.
> It is running hot - at OAT 93F, 2 cylinders are exceeding 400F on
> climbout and oil exceeds 200F.
>
> (BUT EGT's are perfect - less than 45F spread on my EI Monitor)
>
> On runup, no rise in RPM prior to drop on leaning!
>
> All baffling is brand new and installed correctly.
> I have been told that I need to increase fuel flow to improve cooling.
> I don't like going to my A&E without knowing what needs doing, why and
> how (it's a long story :)
>
> So - how do I increase fuelflow on my engine?
>
> Also - Cylinder 5 is too cool - running less than 300F CHT - which means
> it isn't scavenging lead - a recipe for sticking valves. I have been
> told it's because it is out front - but so is cyl 6 and that is one of
> the hottest.
>
> I am running TCP in the 100ll and Avblend in the oil - the engine is
> smooth as silk and has 30 hours on it.
>
> All suggestions highly appreciated.
>
> TIA
>
> Tony
>

[john smith]

Jon Kraus wrote:
> I am not an A & P (nor have I played one on TV) but it sounds like a
> normal occurance in a newly rebuilt engine. I think that once thigs
> break in a little more (and loosen up) you'll see a drop in temps along
> with oil consumption. At least this is according to the rebuild books I
> have read.
> That being said, If I just spent up to 20 AMU's for a rebuild I
> certainly wouldn't hesitate to ask the rebuild shop questions. Good luck!!

What Jon said!
You should be flying at 75% power and full rich until the temperatures
stabilize.

[[email protected]]

john smith > wrote:
: What Jon said!
: You should be flying at 75% power and full rich until the temperatures
: stabilize.

Probably at least. From what I've read, the initial hour or two should be at
a very high power... more than 75% (and of course full rich). Definately sounds like
you've got a couple jugs whos rings haven't seated. Chrome jugs (like mine) are
notoriously hard to get to seat.... particularly if someone put chrome rings on as
well (a no-no).

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Mike Noel]

But it does sound like he may be running too lean based on the no RPM rise
reducing the mixture from full rich. If that is the case, I would suspect a
miss-adjusted carb or an intake manifold leak.


"tony roberts" > wrote in message
news:nospam-97F34F.08333904092005@shawnews...
> Hi
> I have a newly rebuilt 0300-D.
> It is running hot - at OAT 93F, 2 cylinders are exceeding 400F on
> climbout and oil exceeds 200F.
>
> (BUT EGT's are perfect - less than 45F spread on my EI Monitor)
>
> On runup, no rise in RPM prior to drop on leaning!
>
> All baffling is brand new and installed correctly.
> I have been told that I need to increase fuel flow to improve cooling.
> I don't like going to my A&E without knowing what needs doing, why and
> how (it's a long story :)
>
> So - how do I increase fuelflow on my engine?
>
> Also - Cylinder 5 is too cool - running less than 300F CHT - which means
> it isn't scavenging lead - a recipe for sticking valves. I have been
> told it's because it is out front - but so is cyl 6 and that is one of
> the hottest.
>
> I am running TCP in the 100ll and Avblend in the oil - the engine is
> smooth as silk and has 30 hours on it.
>
> All suggestions highly appreciated.
>
> TIA
>
> Tony
>
> --
>
> Tony Roberts
> PP-ASEL
> VFR OTT
> Night
> Cessna 172H C-GICE
>
> --
>
> Tony Roberts
> PP-ASEL
> VFR OTT
> Night
> Cessna 172H C-GICE

[nrp]

Another non-A&P -

Of the two O-300s overhauled among family and friends both had lean
operation problems. The first one others thought might be a little
carb ice (it would smooth out when carb heat was added, a sure sign of
lean operation) until it disassembled itself at about 50 hrs. The
cause was never found.

The second one (a 172H) appeared lean on first annual after OH. We
drilled out the carb jet ever so slightly. I now know that was both
illegal and gauche. But it ran well then to TBO for whatever reason.

I also had lean indications with my 172M (Lycoming) after the one piece
venturii mod - especially on autofuel in the winter.

You might want to make up a test fitting epoxying a 6 inch length of
1/8 inch dia clear plastic hose into a 1/8 inch pipe plug to screw into
the 1/8 inch pipe port in your carb bowl. Using that rig on the
ground, you can find out just where the fuel level stabilizes in the
bowl.

Make sure there are no intake leaks (the gaskets on each cyl adapter
tend to suck in) & that all baffles are in place AND rigid enough that
air pressure doesn't force them away from the fins.

Is the baffle to direct cooling air around the crankcase properly
spaced too? We added a couple of small rubber foot grommets to space
that baffle out from the crankcase. Previously it rubbed on the
casting.

Might your Cyl number 5 thermocouple be miscalibrated?

You might consider the use of the autofuel STC to minimize the lead
contamination. High oil temps and oil that quicly becomes black are a
symptom of piston ring blowby. Lead of course will make it turn gray.

[[email protected]]

Hi Tony;
I also had problems with my 0-300D running at those temps. Turned out
that the ignition timing was 10 degrees over advanced. I found this out
by accident when I had to replace a failing mag myself. Both were
overadvanced. My A&P sweares he checked them at the last annual. Note
that the correct timing mark is a pain to find so some people may be
tempted to pencil whip checking it(If I remember it is on the underside
of the crank when it is at TDC). The two mags are also timed to
different settings. When I reset the timing the engine ran exactly the
same just 100 degrees CHT cooler. Now I can't get it over 400F almost
no matter what I do. Full power cruise is about 375F. Note that the
advanced setting eventually raised hell with my rings and I had to
replace them later on. On the same engine, some time later, I had a
sucked intake gasket that made one of the cylinders run cold along with
a lousy idle.

Jim

[nrp]

Ignition timing is so fundamental to the proper operation of a piston
engine that it should never be taken for granted. Serious owners
should really learn how to check it themselves. Theoretically they are
not permitted by FARs to adjust it, but they are certainly able to
check it.

The Continental O-300D is about the smoothest running engine in
aviation. It has the torsional damper masses on the rear of the
crankshaft that the earlier O-300s don't have.

[tony roberts]

Thanks for all the suggestions - you have given me a few things to look
at.

To clarify a couple of things -
The engine now has 30 hours on it - cylinders are new ECI's.
We switched temp sensors around and got the same results (except oil
temp sensor as we didn't have another one to test with).

Baffles are new - were installed by and A & E and I have had another A &
E inspect them - both say they are good.

There is no excess lead problem - the TCP is doing a great job (Highly
recommended) - the only lead I worry about is on cylinder 5 as it is
running below 300 degrees which is the temp at which the lead scavengers
start working.

Cyl 5 and Cyl 6 both hang out front but there is consistently about 70F
difference between them.

Some of your suggestions I already checked.
Possible causes that I hadn't considered that I got from your responses:

- Timing,
- miss-adjusted carb
- intake manifold leak.

Thanks to everyone - this is one great group - I'll report back when I
find the cause.

Tony
--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

[[email protected]]

: Cyl 5 and Cyl 6 both hang out front but there is consistently about 70F
: difference between them.

Propwash (both in climb and cruise) affect different sides of the engine
differently. It's not uncommon to have different temps on different front jugs
because of this.

: Some of your suggestions I already checked.
: Possible causes that I hadn't considered that I got from your responses:

: - Timing,
Could do it, but should affect all cylinders the same.

: - miss-adjusted carb
Nothing to adjust on non-idle operations.

: - intake manifold leak.
Doesn't affect much at cruise power or above. Not enough relative pressure
difference between the intake ports and ambient pressure.

I'm not saying that these are impossible... they're worth checking. They're
just loosely related different CHT temps at cruise power settings.

Also mentioned by myself and a few others is improper break-in. Just because
there are 30 hours on the jugs doesn't mean they're broken in. Some people fly
engines to TBO on jugs that never broke in. High CHT's, rapid oil degredation, high
oil consumption, and oil-fouled plugs tend to plague such an afflicted engine.
Fortunately, it's not a big deal to pull off a jug or two, hone, new rings, and
re-breakin.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[tony roberts]

Hi Cory

Thanks for your response.

I don't have rapid oil degredation, high
oil consumption, or oil-fouled plug - don't know about the break-in - I
did it by the book but anything is possible.

The guy that rebuilt it is going to have a look - I'll let you know what
happens.

Thanks

Tony
C-GICE



In article >,
wrote:

> : Cyl 5 and Cyl 6 both hang out front but there is consistently about 70F
> : difference between them.
>
> Propwash (both in climb and cruise) affect different sides of the engine
> differently. It's not uncommon to have different temps on different front
> jugs
> because of this.
>
> : Some of your suggestions I already checked.
> : Possible causes that I hadn't considered that I got from your responses:
>
> : - Timing,
> Could do it, but should affect all cylinders the same.
>
> : - miss-adjusted carb
> Nothing to adjust on non-idle operations.
>
> : - intake manifold leak.
> Doesn't affect much at cruise power or above. Not enough relative pressure
> difference between the intake ports and ambient pressure.
>
> I'm not saying that these are impossible... they're worth checking. They're
> just loosely related different CHT temps at cruise power settings.
>
> Also mentioned by myself and a few others is improper break-in. Just
> because
> there are 30 hours on the jugs doesn't mean they're broken in. Some people
> fly
> engines to TBO on jugs that never broke in. High CHT's, rapid oil
> degredation, high
> oil consumption, and oil-fouled plugs tend to plague such an afflicted
> engine.
> Fortunately, it's not a big deal to pull off a jug or two, hone, new rings,
> and
> re-breakin.
>
> -Cory




--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE