The International Cessna^® 170 Association

Hi all—

It's time for a new engine on my 1956 170b. Right now, I have a high-time O300A, but I'm inquiring to see if a C145-2 will fit instead.

There's a low time, recently overhauled C145-2 in my area, and I'm considering purchasing it instead of overhauling my engine. Mainly because it's cheaper than overhaul, available immediately, and has recently undergone and overhaul so I don't have to worry about tearing my engine apart only to find out I need a new crankshaft etc.

My questions—

1. Will a C145-2 fit my 170b?
2. Do I need a new engine mount?
3. Are there any other parts I would need or compatibility issues?

The previous owner is selling everything firewall forward and it came off a 172.

*Please don't advise to upgrade to an O360, out of my budget.

Thanks

-Reece

The U.S. Type Certificate Data Sheet specifies a C-145-2 or -2H for a 170B.

Others can chime in re: the differences between an 0-300A and a C-145-2. As I recall there aren’t any, just Continental changed their designation.

Yes it will fit.

No change in engine mount.

IA DPE wrote: ↑Sat Jun 01, 2024 1:10 am The U.S. Type Certificate Data Sheet specifies a C-145-2 or -2H for a 170B.

Others can chime in re: the differences between an 0-300A and a C-145-2. As I recall there aren’t any, just Continental changed their designation.

Yes it will fit.

No change in engine mount.

IA DPE is correct.

However you say this C-145-2 you are considering, came out of a 172. A C-145-2 was never installed in a 172, is not on the 172 TCDS and if one had been installed, would have required an approval. Before you buy, I'd highly suggest you see a picture of the engine data plate to confirm what engine it actually is.

Is it a field overhaul ?
I’ve seen “D” cases with A crankshafts , so check that it hasn’t undergone a Frankenstein rebuild (8 bolt verses 6 ).
When was the last time it ran ? If it’s been awhile you might be inheriting a new bunch of problems, such as stuck rings or rusted valve springs just waiting to break.
“ Do you feel lucky …. “ (Present day Magnum overhaul cost pointed at your head)

This may not be definitive, but various resources indicate that the 172 was first certified on the Same Type Certificate as the 170, and only later was assigned it’s separate TCDA, per author Rod Simpson.* (However, the prototype 172 so-certified was flown with an O-300-A…. an alternative engine for the 170.)

The 170 type certificate remarks that the O-300-A is the same as the C-145-2, listing it (O-300-A) as an alternative engine on a 170 (see TCDS A-799, item 112).

It may be that reecewallace’s 170 originally equipped with C-145-2 was subsequently equipped with an O-300-A, and if so, installation of a C-145-2 might return it to the original configuration. BUT… it may be worthwhile to confirm the C-145-2 being considered has a “dampered” crankshaft…as that engine was first produced without. This would be important, to me.

(from E-53, engine TCDS) C145 series engines equipped with dampered crankshafts are identified by suffix letter “D” following the
engine serial number which denotes one each 5th and 6th order dampers. O-300 series engines are also
equipped with crankshaft incorporating one each 5th and 6th order dampers.


However, beware that an “D” in a C-145-2 engine serial number does not guarantee a dampered crank…if the previously approved NON-dampered crank was subsequently installed in a repair. Close inspection would be necessary to be absolute in this.

* Simpson, Rod (June 2009). "Cessna 172 – Simply, the World's Most Successful Light Aircraft?". Air-Britain Aviation World. 61 (120). Air-Britain: 158–163. ISSN 1742-996X

c170b53 wrote: ↑Sat Jun 01, 2024 11:57 am Is it a field overhaul ?
I’ve seen “D” cases with A crankshafts , so check that it hasn’t undergone a Frankenstein rebuild (8 bolt verses 6 ).
When was the last time it ran ? If it’s been awhile you might be inheriting a new bunch of problems, such as stuck rings or rusted valve springs just waiting to break.
“ Do you feel lucky …. “ (Present day Magnum overhaul cost pointed at your head)

Jim—it's actually off a 172 at Pitt Meadows. It was recently overhauled and has not been sitting. Flown 300 hours in the last three years. The owner is selling to upgrade to more HP.

Okanagan Aero Engine overhauled it in 2021. I'll request a photo of the engine data plate.

GAHorn wrote: ↑Sat Jun 01, 2024 1:25 pm This may not be definitive, but various resources indicate that the 172 was first certified on the Same Type Certificate as the 170, and only later was assigned it’s separate TCDA, per author Rod Simpson.* (However, the prototype 172 so-certified was flown with an O-300-A…. an alternative engine for the 170.)

The 170 type certificate remarks that the O-300-A is the same as the C-145-2, listing it (O-300-A) as an alternative engine on a 170 (see TCDS A-799, item 112).

It may be that reecewallace’s 170 originally equipped with C-145-2 was subsequently equipped with an O-300-A, and if so, installation of a C-145-2 might return it to the original configuration. BUT… it may be worthwhile to confirm the C-145-2 being considered has a “dampered” crankshaft…as that engine was first produced without. This would be important, to me.

(from E-53, engine TCDS) C145 series engines equipped with dampered crankshafts are identified by suffix letter “D” following the
engine serial number which denotes one each 5th and 6th order dampers. O-300 series engines are also
equipped with crankshaft incorporating one each 5th and 6th order dampers.


However, beware that an “D” in a C-145-2 engine serial number does not guarantee a dampered crank…if the previously approved NON-dampered crank was subsequently installed in a repair. Close inspection would be necessary to be absolute in this.

* Simpson, Rod (June 2009). "Cessna 172 – Simply, the World's Most Successful Light Aircraft?". Air-Britain Aviation World. 61 (120). Air-Britain: 158–163. ISSN 1742-996X

Thanks for all the info

Yes—the engine does have a dampered crankshaft with a 'D' in the serial #.

Reece, that’s a quality shop, nice pick up.

I ran a C-145-2 (with the “D” in the serial number) for a few years, and the changeovers both ways were just airframe log book entries. I used the original mount for both engines. Other than the “D” serial numbers designating a dampened crankshaft, if you look at the IPC for this series of engines, you'll be hard pressed to find any differences in part numbers between the C-145-2 and O-300A. I’ve heard (but never substantiated) that some older C-145 engines may have had cast iron cams and steel lifters rather than the opposite, and there may have been other minor, inconsequential differences, but are essentially the same engine.

My 170B is serial number 26541, the 37th 170B to be designated as as a 1955 year model, and the engine installed at the factory (and currently on the airplane) is an O-300A, serial number 10043-D-4A, which I assUme is an early production engine with the O-300 designation. This leads me to believe that most if not all 1955 and 1956 year model 170s would have had O-300A designated engines installed at the factory.