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juno · Posted: Tue Dec 18, 2007 5:41 am Post subject: New engine run in procedure

Just had my engine rebuilt on my 931. Turbo was new from KKK about 7000 miles ago. Wastegate is off ebay, but seems to be in very good condition, possibly rebuilt at some point in the past.

Should I run it in as Paul suggests in this thread? http://www.924board.org/viewtopic.php?t=9821&highlight=engine+break
Doesn't say 931 so wanted to check.

It's coming from the garage with Helix 10/40 oil and about 4 miles on the clock. Do I need to swap this out for mineral oil, then switch to mobil 1 as described in that thread, and if so which grade at each stage is reccomended? it's around 32-42 F here at the moment.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Paul's break-in procedure is sound but a little too complicated for me. I'm both a little lazy and impatient though. The engine builder has already done the important part during the first warm-up cycle so nothing you can do there. I like to rev my engines a little harder than Paul suggests but don't abuse them at red line. During the first 100 miles go ahead and redline in a gear or two AFTER it is fully warmed up. Spend most of your time below 5000 rpm and be sure to vary your engine speed as much as possible. Try not to cruise for extended periods of time and definitely do not let it sit and idle for the first 500 miles.

Most of the professional engine builders I talk to are now suggesting the use of diesel motor oil for the 500 mile break in period. Something to do with the high sulfur content being very easy on cams and bearings but still allowing the rings to seat. You might research that a little.

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....

juno · Posted: Fri Dec 28, 2007 10:07 pm Post subject:

Checked with the builder, they agreed so we dropped the oil and refulled with 10/30 diesel motor oil.

Done about 300 miles in it so far. Taken it to the redline two or three times after it's been running for an hour or so. Really seems to shift, just feathering the throttle. I can also hear the turbo spinning, which I've never been able to before.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

juno · Posted: Wed Jan 02, 2008 10:20 pm Post subject:

Helix as in Shell Helix: http://www.shell.com/home/Framework?siteId=uk-en&FC2=/uk-en/html/iwgen/leftnavs/zzz_lhn3_3_0.html&FC3=/uk-en/tailored/shell_for_motorists/oils_lubricants/helix_new/products/dir_helix_products_ga_0707.html

Just spoke to them. Starting to get worried now as they don't seem to have done what they originally said or asked. I asked for a full rebuild with a rebore. The block hasn't been rebored but pistons are new standard size Mahle. Bores were checked for roundness by measuring in several places. They have just been shined up. The head had a new cam about 50k ago, so that's not been replaced but it's had new valves & guides.

Also annoyingly there is a metallic rattle noise coming from the turbo area when the car has warmed up. From searching here it seems it's probably nothing major to worry about, just really annoying as the rattle just happens at 30 mph in 3rd gear, and 35 in 4th! just about town speed. Plus the cost of dismantling it all again to fix something that wasn't wrong before, and especially after laying out nearly £4000 in total with the new clutch.

I ask about the oil as the mechanic said I shouldn't be using Mobil 1 on a car of this age. It's also considerably more expensive here, around £36 for 4 litre, so an oil change means 2 containers. It's also a special order, and I am told that distributors are starting to delete it from their stock list. Just really thinking of the future as it's getting really hard to get, don't mind paying for it.

Starting to lose faith in this mechanic now, so I would really appreciate any advice anyone can give me.

thanks, j
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

924aussie · Posted: Wed Jan 02, 2008 11:14 pm Post subject:

First off I would be getting a detailed receipt of what he did do

Alan
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green 924 .. 1980 rego 924PSH
1998 Mopar Neon ... sick
2003 Challenger / Montery 4WD
1995 Hyundai Scoupe ... sold
1998 Nissan Silvia ... sons back from OS he has taken it
BIG BLOODY MOTORHOME 300zx Sold
1980 Fire truck Sold

juno · Posted: Thu Jan 03, 2008 12:35 am Post subject:

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Wouldn't complain about retaining oil pressure. . .that's the sign of a nice tight motor. What are your oil pressures running (hot and cold, 3k and idle)?

The rattle may be the turbo recirc valve. Check it out in our FAQ HERE.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

John Brown · Joined: 07 Nov 2002 Posts: 903 Location: Leesburg VA

juno · Posted: Thu Jan 03, 2008 7:59 pm Post subject:

juno · Posted: Thu Jan 03, 2008 9:43 pm Post subject:

just got logged out from the board and lost a reply to JB that took ages! aagrh, will type it again later. Off to lay into this mother now and get some real answers.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

juno · Posted: Mon Jan 07, 2008 1:55 am Post subject:

Aparrently the main problem was the top ring had broken and damaged the piston crown, but not the bore. Here is a couple of pics of the damaged piston:

And while I've got the camera, Some pics of the old wastegate. There are 4 small holes in each corner.

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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

juno · Posted: Mon Jan 07, 2008 2:04 am Post subject:

Right, it's not diesel oil that's been put in, it's shell helix supa 10/40. Ugh, don't you just hate people that tell you what you want to hear regardless.

Noticed it seems to be burning a fair bit of oil, it's now 75% the way down the min/max markers in 400 miles, and it's looking very black, and there is oil coming out from the charge pipe to the join to the throttle body. Is this a sign that the turbo is faulty, or could it be to do with the recirc valve rattling? The turbo has supposedly been checked and found to be good by the same people who did the engine.

here's a pic, it's hard to see, there was more black oil around the join, I wiped some of it away with my finger.

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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

juno · Posted: Mon Jan 07, 2008 2:43 am Post subject:

Also it's popping and farting like mad after revving, sounds really bad when decelerating in gear, a really nasty warbling sound. Been round checking tightness of things around the engine, pipe from the air box was really loose, tightened it up along with the charge pipe join to throttle body. also tightened the exhaust bolts up near the turbo as they were a bit loose. this has definately made it run differently, it sounds better and idles better but it's not starting quite as well, takes 4-5 seconds to fire up even after 10 minutes of being off from warm.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

Smoothie · Posted: Mon Jan 07, 2008 2:54 am Post subject:

I'd say that piston damage is from detonation rather than a broken ring. Normally, when a ring breaks, it just splits across (radially) then stays in the ring land (recess) - there shouldn't be enough room for part of a broken ring to sneek by between the piston and cylinder and find its' way to the top of the piston. -And that bit of damage at the upper-side shown in the first pic - if not caused by a piece of metal that somehow found it's way to the top of the piston [unlikely], might have happened while the piston was being removed, if it were pushed out the top of the cylinder before a ridge-reaming was done[, and a bit of overhanging detonation damage (melted edge) caught the ridge on its' way out]. [The other nicks that appear to have been hammered into the piston by a loose piece of metal are actually consistent withwhat they're calling "Abrasion (pitting of the piston crown)" here - http://www.contactmagazine.com/Issue54/EngineBasics.html ]

The recirc valve wouldn't be an oil leak source, rattling or not. What you're describing is likely due to either a large amount of blowby or the turbo seal's leaking excessively. Of course either of those would account for the excessive consumption as well. -But the black oil would be more likely due to excessive blowby. If the rings don't seat and the excessive consumption continues, you may have to pay the rebuilder another visit.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox