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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 291
Location: Parkville, Maryland
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 Posted: Mon Jun 23, 2025 1:41 pm Post subject: Top End Rebuild Break In |
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Hi all. I am nearing completion on a top end rebuild, and I am wondering about break-in procedures. I have seen oodles of threads about break-in procedures for complete engine rebuilds, but maybe only one about procedures for a top end rebuild.
I had a hole in a piston face (see one of my previous threads for a pic), so I did a top end rebuild consisting of a top end rebuild kit from AA … 88mm thick-walled pistons, cylinders, and new heads bored out to accept the cylinders.
So I have read about driving the car up and down hills, in gear (2nd or 3rd) to help the rings seat. Do that for how long, say for like 15 mins? Once that is done, along with a little non-highway driving around to vary RPMs, would I change the oil after that, or wait a couple hundred miles to change it?
Are there any other elements of the break-in procedure I’m missing?
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67rustavenger
Samba Member
Joined: February 24, 2015
Posts: 11080
Location: Oregon
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| Posted: Mon Jun 23, 2025 2:48 pm Post subject: Re: Top End Rebuild Break In |
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| Snoopy1971 wrote: |
Hi all. I am nearing completion on a top end rebuild, and I am wondering about break-in procedures. I have seen oodles of threads about break-in procedures for complete engine rebuilds, but maybe only one about procedures for a top end rebuild.
I had a hole in a piston face (see one of my previous threads for a pic), so I did a top end rebuild consisting of a top end rebuild kit from AA … 88mm thick-walled pistons, cylinders, and new heads bored out to accept the cylinders.
So I have read about driving the car up and down hills, in gear (2nd or 3rd) to help the rings seat. Do that for how long, say for like 15 mins? Once that is done, along with a little non-highway driving around to vary RPMs, would I change the oil after that, or wait a couple hundred miles to change it?
Are there any other elements of the break-in procedure I’m missing? |
Do the hill climb 3-4 times. Full throttle up and down, on the down side, let the engine do the compression braking and vary the throttle a little.
Let it cool and change the oil the following day. It'll be a little shimmery (fine silver looking particles) when you drain it.
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Bobs67vwagen
Samba Member
Joined: March 27, 2005
Posts: 344
Location: Eastern north carolina
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| Posted: Mon Jun 23, 2025 3:17 pm Post subject: Re: Top End Rebuild Break In |
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| I concurr with 67rust. I was always told to vary speed often and do a lot of around town. Up and down type engine revolution for about. 2 days and any ring seating will be complete. I think the worst thing you can do for break in is to keep the engine at steady rpm for more than a few minutes. |
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 291
Location: Parkville, Maryland
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| Posted: Mon Jun 23, 2025 3:36 pm Post subject: Re: Top End Rebuild Break In |
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| 67rustavenger wrote: |
| Snoopy1971 wrote: |
Hi all. I am nearing completion on a top end rebuild, and I am wondering about break-in procedures. I have seen oodles of threads about break-in procedures for complete engine rebuilds, but maybe only one about procedures for a top end rebuild.
I had a hole in a piston face (see one of my previous threads for a pic), so I did a top end rebuild consisting of a top end rebuild kit from AA … 88mm thick-walled pistons, cylinders, and new heads bored out to accept the cylinders.
So I have read about driving the car up and down hills, in gear (2nd or 3rd) to help the rings seat. Do that for how long, say for like 15 mins? Once that is done, along with a little non-highway driving around to vary RPMs, would I change the oil after that, or wait a couple hundred miles to change it?
Are there any other elements of the break-in procedure I’m missing? |
Do the hill climb 3-4 times. Full throttle up and down, on the down side, let the engine do the compression braking and vary the throttle a little.
Let it cool and change the oil the following day. It'll be a little shimmery (fine silver looking particles) when you drain it. |
Thanks ... yes, I was fully expecting a glitter party when I drain it!!
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 4488
Location: viroqua wi.
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| Posted: Mon Jun 23, 2025 4:42 pm Post subject: Re: Top End Rebuild Break In |
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| I agree with the others, load it good and let it Jake brake. A hill works but not necessary. Get it to temperature and run it hard. I would drain it hot and clean the screen. I also use Brake clean with a straw and blast the inside of the sump real good. |
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BMFBMF
Samba Member
Joined: November 13, 2020
Posts: 462
Location: Swtzerland
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| Posted: Tue Jun 24, 2025 10:25 am Post subject: Re: Top End Rebuild Break In |
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I would break it in normally but use 20w50 break in oil to avoid the modern friction modifiers that cause glazing. For example Lucas 20w50 break in oil, I'd run it a few hundred miles.. You can take a chance with "cheap oil" not having friction modifiers, but it's risky.
For 30 bucks of oil I'd put luck on my side.
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1971 Stock South African Beetle 1300 : My mom's european "Thin Chick" spec. Completely stock with torsion bar front, swingaxle rear, smooth hubs, single MC, 40 mm shoes, 31PICT3 carb and 5 bolt drums all round, currently Running a 1976 SF:AS engine with the original SF:AD engine overhauled in a box, waiting to go back in one day. |
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Snoopy1971
Samba Member
Joined: May 15, 2020
Posts: 291
Location: Parkville, Maryland
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| Posted: Tue Jun 24, 2025 2:29 pm Post subject: Re: Top End Rebuild Break In |
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| BMFBMF wrote: |
I would break it in normally but use 20w50 break in oil to avoid the modern friction modifiers that cause glazing. For example Lucas 20w50 break in oil, I'd run it a few hundred miles.. You can take a chance with "cheap oil" not having friction modifiers, but it's risky.
For 30 bucks of oil I'd put luck on my side. |
Yep, I already have some Lucas 20w50 bdreak in oil for this!! 
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