New 3.4 break in question...from the main forum.

[fallingat120mph]

Just for piece of mind I wanted to ask here.

So, 3.4 build is done and up and running. Car was accepted to LUFT 11 and I am about 20 hours away. Here is where I am:

New P&C
New cams
Twin plugged
Chipped (Steve W.)
New exhaust
and some other stuff, rockers redone, etc...


So this wasn't just a top end and my shop and I have so far done the standard break in. Fired it up on the stand, everything checked. Ran it at certain rpm for certain times.

Without getting crazy in the weeds with the different break in procedures the engine is in the car and running great at this point it has about 50-60 miles on it driving it tastefully hard on two separate occasions to get some load on it.

Oil has been changed, of course, and valves re-adjusted. Everything is great but my concern is I am not sure how many miles I can get on it before I hit the highway heading to LUFT/Durham, NC in a few days.

Through the years it seems 500 miles is the standard for getting on it under load, etc. but am wondering if I can get 200-250 on it and drain that oil and check the valves if that will be enough time/distance?


I know this is bordering an oil thread with opinions varying but I am curious if two days of highway driving will hurt it after a not so lengthy break in.


It seems like everything at this point should be pretty bedded in but know 500 miles is the standard...no way I can get there in a day and a half without driving it continuously which I think goes against the "break in period" common practice.

Just curious to hear from some of you...


Thanks!
Erik

[snbush67]

Start with a leak down to see where you’re at. Yes, at 500 miles you probably are minimally broken in. Go do multiple long pulls uphill starting in the wrong gear and taking it all the way to redline, and do some light engine braking downshifts. Drive like an idiot for about an hour, do pulls in each gear through redline. That should get the rings completely seated. Take another leak down.

[85RedCarrera]

Congrats on getting it back on the road!

[Locker537]

Sure sounds like the trip to Luft would be the perfect way to fully break it in.

Take some detours on nice roads.

[fallingat120mph]

Originally Posted by snbush67

Start with a leak down to see where you’re at. Yes, at 500 miles you probably are minimally broken in. Go do multiple long pulls uphill starting in the wrong gear and taking it all the way to redline, and do some light engine braking downshifts. Drive like an idiot for about an hour, do pulls in each gear through redline. That should get the rings completely seated. Take another leak down.

My shop has been doing exactly that. I am an hour away and there was some body work done so sadly I haven't had it home yet. Hoping today. Live in a very hilly part of Missouri with great farm roads so getting on it should be easy.

Originally Posted by 85RedCarrera

Congrats on getting it back on the road!

Thanks! From the videos it looks and sounds spot on. As stated I live quite a ways away so my shop has taken the reigns for the first 100 or so miles on break in.

Originally Posted by Locker537

Sure sounds like the trip to Luft would be the perfect way to fully break it in.

Take some detours on nice roads.

Yeah, it will add time but already looking for routes that are back road. Tail of the Dragon is a nice story for my "break in".



Thanks all....
Erik

[kamaro]

Rule #1 on ANY newly rebuilt engine : don't let it idle for too long (don't let it idle at all if new cams are in).

#2 : ensure to break in your new cams but starting it and right away rise the idle to 2k rpm and then let it range between 1500 to 2500 rpm from time to time for 20 min. I like to do it in a separate 10 min + 10 min where I turn it off in between just to check.

#3 : change your oil/filter.

#4 : if all is good now take it out and look for a slight uphill road, go up the road on a high gear to redline and then turn around and go down using engine breaking, do that 3 times and you are done.

#5 : drive it like you stole it, just redline it on every gear! don't bother with the 500 miles thing.

[fallingat120mph]

Well, got the car on the road and everything was great - until they weren't.

Ended up having to trailer the car home.

Long story short got about 4-5 hours in the trip and out of nowhere had a stall on the road. At first I thought it was the road, or the truck passing by...I noticed something but wasn't sure.

Then after another few minutes the car sputtered, back fired, and I knew to head to an exit. As I was exiting the car sputtered a bit more and then just died. I coasted to a stop.

There was a gas station a few miles up and after the car cooled a bit went against everything I had I fired the car up and it sounded great. Crossed my fingers to get to civilization and got back on the road where everything was fine.

As I got closer to the exit noticed the temp was warming back up to normal and that's where it starting to want to cut out again. Saw the exit and got more speed and just as I saw the gas station from the highway the car cut out and stalled. By some miracle I was able to coast from the highway, off the exit ramp and to a parking spot at the gas station for the night.

At first it felt like a bad gas sputter. Growing up in the Midwest in the 70's and 80's this was a thing.

So, short story longer, the next morning I found a uhaul truck and auto transport a few miles away and decided against everything to see if I could get the car there as it was around 10-12 miles away. Car fired up and sounded fantastic so got it on the road and sure enough once it got back up to normal temps it cut out. I finally made it to another small town station and hitched a ride to the uhaul.

Overall, once cooled it starts and runs fine. Not sure why it ran so well after 4-5 hours and then just decided not to.

I know most of the sensors have been replaced/updated.
Vacuum lines all seem proper.

What I did notice this morning is with the key on the ICV is humming but it's also pulsing which I don't remember in all my years.

Bad DME would mean no start, correct?

Been reading through posts trying to figure out if I can bench test sensors or where to start looking.

Certain sensors. Maybe fuel starvation?



Been a long couple days and nights, and bummed I didn't make it to LUFT 11. With the money invested in this build that was the least of my worries.

As with most of you I will be hyper focused on things for the next few days so any advice to this novice engine builder/mechanic is welcome.


Erik

[silverlock]

A few things that come to mind:

- Check the resistance on your Cylinder head sensor (CHT). Should be ~1040 Ohms at 68F ambient, ~180 Ohms around 210F and down to 90 Ohms > 230F. See https://forums.pelicanparts.com/porsche-911-technical-forum/1052215-verify-my-cht-sensor-test-results.html#post10747620
- Inspect & reseat the speed & ref sensor connectors + harness. Check their resistance as well, especially when hot. Should be ~1k at 68F as well, +/- 10% or so.
- Inspect the 4-pin connector at the back of the engine bay. Ensure the harness isn’t somehow absorbing too much heat / routed poorly.
- Try another DME relay (plus good to have a spare on hand anyway!)
- Try priming (via jumping) the fuel pump after it happens. Does it run? Run OK?
- Coil: although less likely, a lot of these Bosch coils like to gradually fail. Heat doesn’t help.

A power cut due to heat points at a few of those things. Sorry to hear this got in the way of enjoying Luft. Was just in the neighborhood for Targa Carolina earlier in the week!

[Mr. Merk]

Bummed we didn't see you out there. We walked all over looking for your car.

Sounds like it might be an ignition module failing when heating up (hence the attached heat sink). I'd imagine it would fail sooner each time until it eventually wouldn't work at all, even fully cooled.

I know another guy that's had a bunch of issues with the new modules. We've had poor luck with the quality of many new parts, even Genuine Porsche.

[fallingat120mph]

Originally Posted by Mr. Merk

Bummed we didn't see you out there. We walked all over looking for your car.

Sounds like it might be an ignition module failing when heating up (hence the attached heat sink). I'd imagine it would fail sooner each time until it eventually wouldn't work at all, even fully cooled.

I know another guy that's had a bunch of issues with the new modules. We've had poor luck with the quality of many new parts, even Genuine Porsche.

Much appreciated in regards to seeking me out. Same would have held true if I had made it - was excited to meet up also.

Immediately swapped out modules and no dice. Both are working fine as far as I can tell.

Now home, what a mess. Not a religious fellow per se but the universe was looking out for me. By pure luck I had gotten off the back roads in Illinois and coasted off the interstate to my parking place for the night in a parking lot. Car was running fantastic until it wasn't.

Anyway, two sleepless days/nights and home now I have started looking into things. CHT seems to be in the right parameters, modules seem fine. Car starts up fine and idles fine, strong actually, but on the road as soon as it get warm is when the problems begin. I need a week of doing nothing and then will get with the shop and see what direction to go.

HOPEFULLY, Palooza is still in the cards for me.


Hope you had a great time. Very expensive no show for me, so hope those of you who got to attend have good stories for me when we finally meet in person.


Erik