914 engine rebuild

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neilbardsley
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914 engine rebuild

Post by neilbardsley »

I thought some might be interested in the process. My 914 engine was using a lot of oil so I gave to Alan at AHS to investigate.

History

I bgt the car in 2020ish and had the engine rebuilt to 2l. Moderate cam with about 130hp. Alan claimed to get a bit more when he had it on his rolling road.

I added an extra tuna can slump. Temperature, oil pressure and Air/Fuel Ratio gauges. All good prevention steps. I hoped.

We had quite a few good trips in it. However, on the last trip I noticed it wasn't idling as well and not accelerating as before.

Alan when setting the valves commented that he didn't think the pistons rings had completely sealed.

It took me quite a while to find out that one of the Weber floats had a hole in it so was overfilling the bowl.

Next a disaster struck when I lost the slump plug and all the oil from the engine.

After refilling I hoped I had got away with it but I was consuming a lot of oil.

The car sat for about 3 months at AHS waiting it's turn.

First when the engine was dropped Alan discovered the crank seal was leaking.



I guess we could of stopped there but we agreed to carry on. The plan was to take the heads off and check the big ends.

Next call I got was that the case was open. Main bearings gone, crank/case std/std. Top of valves gone. Maybe some cam followers. Some rings never sealed. The Alan thinks I switched to full synthetic too quickly.

Complete disaster avoided


Next steps

12 week wait for new rings
New bearings
New valves
Rehone pistons

Back together ImageImage

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
Bruce M
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Re: 914 engine rebuild

Post by Bruce M »

Like a good engine story
rhd racer
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Re: 914 engine rebuild

Post by rhd racer »

Crikey


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93 964 C2
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hashman
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Re: 914 engine rebuild

Post by hashman »

Sorry to hear you've had a bad time with this engine so far.
Look forward to hearing of a happy ending Neil.

Karl
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Nine One One
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Re: 914 engine rebuild

Post by Nine One One »

Do you think your woes with the 356 engine were caused by the 20w 60 synthetic oil you put in it for the trip?
Nine One One
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Re: 914 engine rebuild

Post by Nine One One »

Nine One One wrote: Wed May 13, 2026 11:03 am Do you think your woes with the 356 engine were caused by the 10w 60 synthetic oil you put in it for the trip?
neilbardsley wrote: Thu Apr 02, 2026 9:07 pm Got some special oil for the trip. This is 10/60 synthetic. It will be very stable for some of the longer days. Probably over kill as ehe old oil only had a few hundred miles on it and came out pretty clean.

I'm still working on my Power Point Present on oil for dinner at the next annual meet?Image

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70sThrowback
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Re: 914 engine rebuild

Post by 70sThrowback »

sounds similar to my build issue. Started with a bent valve, but on advice I allowed them to open the engine to discover big end bearing wear, and forgive my non-technical explanation, but the dowel?? hadn't seated correctly? New bearings, rings, pistons and back on the road. But like you Neil it was an engine waiting to explode at some point. Now I am back on the road building confidence, but I am a lot happier with the garage, the builder and the process. So this is my anxiety of being let down, rather than anything wrong with the car now. I'm off to the Wild Atlantic Way on saturday in it which will be a great test.
Jonny

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anglophone1
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Re: 914 engine rebuild

Post by anglophone1 »

see you Tuesday Jonny!!
C
Clive
West Cork, Ireland

RGruppe #814
1978 SC/1984 3.2 Outlaw -Jaffa 911
1973 914 - on Webers - historic rally car- Tango 914
1977 924 2.0 on Webers street legal race car - Martini 924
1975 911/Flachbau 930 clone- too cool for school! 8)
neilbardsley
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Re: 914 engine rebuild

Post by neilbardsley »

Nine One One wrote:
Nine One One wrote: Wed May 13, 2026 11:03 am Do you think your woes with the 356 engine were caused by the 10w 60 synthetic oil you put in it for the trip?
neilbardsley wrote: Thu Apr 02, 2026 9:07 pm Got some special oil for the trip. This is 10/60 synthetic. It will be very stable for some of the longer days. Probably over kill as ehe old oil only had a few hundred miles on it and came out pretty clean.

I'm still working on my Power Point Present on oil for dinner at the next annual meet?Image

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No is the short answer but until I get the car back to investigate I can't say for sure. I had zero concerns about the engine until about 20/30 mins before we stopped. I heard the engine note change. Then 10 mins late I pulled over because it felt unbalanced/rough to check. Then 10/20 mins later we were stuck.

Alan's comment about mineral was for breaking the rings. The full synthetic is too slippery. The rings in the 356 should of settled years ago.

Alan was talking about mineral oil being a better sealer for the rings so producing more power but synthetic being more stable under higher temperatures so better for wear. Interesting he said he uses full synthetic in this race cars but it's quite special/expensive.

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Bruce M
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Re: 914 engine rebuild

Post by Bruce M »

Sinking float could end up washing the bores & wearing the rings.
Loss of oil pressure (sump plug problem) will wipe out the bearings immediately (rod bearings come after mains so suffer if oil flow is poor).
I like a big oil pump & thinner synth oil but that is a very controversial subject.
neilbardsley
Nurse, I think I need some assistance
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Re: 914 engine rebuild

Post by neilbardsley »

Good point the rings not sealing could be fuel washing down the piston.

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“A REMINDER. I would be grateful if those members who have borrowed bits from me in emergencies (e.g starter motor, oil cooler, etc) would return them and/or contact me”. – Chris Turner RIP
911hillclimber
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Re: 914 engine rebuild

Post by 911hillclimber »

Why not just use ordinary semi synthetic from Shell etc?
Bob Watson told me to use only Shell Helix 30+ years ago on all my hot and stock engines, all ok after 34 years.

Simple, but that’s just me. :drunken:
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70sThrowback
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Re: 914 engine rebuild

Post by 70sThrowback »

anglophone1 wrote: Thu May 14, 2026 12:31 pm see you Tuesday Jonny!!
C
Absolutely Clive - though the weather looks errm Irish ;)
Jonny

Current custodian of 1976 Porsche 912E, 1973 VW Camper
anglophone1
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Re: 914 engine rebuild

Post by anglophone1 »

Ping me Pm where you are Monday night and Tuesday route please?
c
Clive
West Cork, Ireland

RGruppe #814
1978 SC/1984 3.2 Outlaw -Jaffa 911
1973 914 - on Webers - historic rally car- Tango 914
1977 924 2.0 on Webers street legal race car - Martini 924
1975 911/Flachbau 930 clone- too cool for school! 8)
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