The International Cessna 170 Association

Updating an older thread.

Since I’ve owned my airplane it has taken about 30 seconds to show oil pressure on start up. Last December with cold oil it was taking almost two minutes.

We put a gauge right on the engine and it was showing pressure right away, so we knew the engine was ok. Replacing the copper line engine to firewall (with copper) didn’t improve it.

I installed a new gauge and blew out the copper line from the firewall to it, and replaced the new copper line engine to firewall with a hose from PHT. We put kerosene in both lines, and I now have a pressure indication in four seconds.

The 17.5” hose was $75 but not having to worry about a failure and having an immediate and accurate indication is worth it.

IA DPE wrote:Updating an older thread.

Since I’ve owned my airplane it has taken about 30 seconds to show oil pressure on start up. Last December with cold oil it was taking almost two minutes.

We put a gauge right on the engine and it was showing pressure right away, so we knew the engine was ok. Replacing the copper line engine to firewall (with copper) didn’t improve it.

I installed a new gauge and blew out the copper line from the firewall to it, and replaced the new copper line engine to firewall with a hose from PHT. We put kerosene in both lines, and I now have a pressure indication in four seconds.

The 17.5” hose was $75 but not having to worry about a failure and having an immediate and accurate indication is worth it.

You did exactly what I feel everyone should do. Congratulations!

George:

Given the multiple failures of the copper line engine> firewall, would this not be an item to add to the Recommended Modifications/ Maintenance Sticky? At the least replace the copper line if there's no record of that being done, otherwise switch it to hose? After reading the story of Cleo down on the AlCan Highway, and Jim's recent one, that was what changed my mind.

IA DPE wrote:George:

Given the multiple failures of the copper line engine> firewall, would this not be an item to add to the Recommended Modifications/ Maintenance Sticky? At the least replace the copper line if there's no record of that being done, otherwise switch it to hose? After reading the story of the one down on the AlCan Highway, and Jim's recent one, that was what changed my mind.

Done! Thanks for the suggestion!

I’ve seen one length of hose mentioned at 17 inches . Wondering what length others have used. Also any photos of oil pressure line from the firewall to the engine case would be appreciated. I can see several potential routings and would like to see how others have done it.
Thanks, Frank

I don't have a picture of the routing and won't be to the hanger for several days, but I just used a That Looks About Right approach. Somewhere either in this thread or another I saw someone else used 19". That likely worked as well- I just felt it was a little too long for me.

Thanks! When it’s convenient for you I’d still like a photo. A hose mfg suggested using a piece of vacuum hose as a measuring tool. We did so today and the routing we use, with some slack, was 29 inches . Sounds too long, but that’s what it measured. One other post mentioned 17”. I’m still several weeks from getting a hose made until I get more accurate numbers.

170C wrote:Thanks! When it’s convenient for you I’d still like a photo. A hose mfg suggested using a piece of vacuum hose as a measuring tool. We did so today and the routing we use, with some slack, was 29 inches . Sounds too long, but that’s what it measured. One other post mentioned 17”. I’m still several weeks from getting a hose made until I get more accurate numbers.

Frank, are you measuring from the FIREWALL to the engine fitting...? Sounds like you’re trying to take it from the gauge to the engine. If you intend to do that, you should use two hoses and a bulkhead fitting.

No George. We were going from firewall to the fitting on the engine. Didn’t think the hose would fit exactly where the copper line goes vertically behind the cylinder baffle. I was told there needed to be some slack in the hose. That is why I would like to see how others routed the hose, etc.

Of COURSE there should be some slack in the hose. It should allow for engine movement and never be taut. YOUR installation may be different than others. What you should do is take a tape and measure the straight-line distance from firewall to engine fitting, add a couple of inches and that should be your minimum length.

I use a sewing tape measure to determine the length of flexible hoses needed. It's much more flexible and easier to use than a metal tape. You can usually find them in the sewing section of your local CVS, Walgreens, etc.
My oil pressure hose (firewall to engine) measures out at 19". But it's likely that your length will differ depending on your model, location of your oil pressure guage, where the line goes through the firewall, routing, etc.

Yea, I think I may have one of those sewing tapes in my toolbox. If not I can slip one of my wife’s. I suspect my existing copper line is pretty much identical to other installations. I appreciate all the input.