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Discussion Starter · #1 ·
A quick rundown of what's happened here:

Bought 2002 9-3 with 80,000km on it.

Added Nordic Stage 3 ECU, upgraded FPR, 3" downpipe, various suspension upgrades.

Ran fine until 100,000km when it started stalling at lights after a small road trip.

Diagnosis - broken piston skirt.

Engine mic-ed at reputable machine shop - all measurements were within spec, except for excessive cylinder wear in all cylinders and double-bad wear in the #3 cyl - the one where the skirt broke.

bored, honed, planed polished. One over JE forged pistons and rings installed. Note: machine shop put together the pistons (wrist pins, spiro locks) while i did the rest of the rebuild myself.

Replaced tons of parts on the rebuild including the fuel injectors. I got those tested and they produced good pressure, but leaked when closed.

One though is that they leaked, washing the cylinders causing excessive wear.

Anyways, engine back together. Castrol GTX 10W30 for the first 3500 km. Amsoil 5W40 synthetic since then. A month back, with 3900km it started getting hard to start when cold.

Outside temps getting colder, and it seems directly related to the temp that the engine stumbles when starting. After starting once, it would start again nicely for the rest of the day.

Took it in to the local import specialist. I like their work and the owner is an old European guy - the type who seems to be able to diagnose what's wrong with a car just by sniffing the gas cap.

They couldn't find anything definitely wrong. So he says change oil out for 10W30, use 91-94 octane gas with no ethanol (my last few fillups were a high octane gas but with a high ethanol content too) and maybe change the battery. He also says, just off-hand, that he can hear a wrist pin knocking but he is not too worried about it. So he sends me home, says to monitor it and not to worry..."you did a good job on the rebuild" ..

It's this last part that kept me up last night - I am very worried that he hears a wrist pin knocking and I am not confident enough with my engine rebuild skills to just monitor it. Is the hard-to-start when cold issue actually an engine gradually seizing from bearing friction, or ...?

So I got the automotive stethoscope out and I can hear a knock that seems louder near cyl#1. Some *internet research* makes me think its more like rod knock than wrist pin knock but anyways...I think I should get a second opinion.

Thanks for any advice.
 

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Forged pistons are notorious for being noisy. Also, using a 10w oil instead of a 5w oil in the winter is counter intuitive.

5w-XX should flow easier and start easier than a 10w-XX oil at cold temps. The number with the 'w' next to it indicates what weight of oil it behaves like at cold temperatures. Saying 5w-40 is a oil that has the viscosity of a 40 weight at operating temperatures and behaves as a 5 weight oil would at cold temps.
 

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Forged pistons will make a little more noise than stock ones on cold startup, especially when it's really cold.

Just did a customer's SPG with Crower rods and Wossner rods, all new timing chain, Clevite bearings, etc. and it is a little clattery at idle at cold start, was the first time we cranked it over, and still is after about 1,200 breakin miles. I have basically the same setup in my C900T but with new old-stock Mahle pistons and stock rods, and it is much quieter at idle than this one is.

I wouldn't worry about it unless it gets really noticeable.

You might consider getting an oil pressure guage to keep an eye on it though, when a bearing starts to go you will get lower and lower oil pressure, you can keep a little better eye on it more objectively that way.
 

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Discussion Starter · #4 ·
Thanks for the replies - I sure hope that it's just the new forged pistons being rattly.

I actually have an oil pressure sandwich already installed inline with the oil filter, I just have to get the wires through the firewall and figure out where to put the gauge.
 
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