inactiveuser92616

So,
I am pretty sure that I have rod knock.

For the past week my car has sounded like it has an exhaust leak, making a loudish sound upon acceleration or under high load.

Today while filling pulling into the gas station, my oil pressure dipped below 2 bar briefly and threw the light, but came right back. Drove home, and on the highway while cruising felt a sudden loss of power. Pulled onto my own road and a horrible rattling sound started going, nursed it the mile home. Now it sounds like a diesel without a muffler, even at idle.

Rod knock?

It also started pissing coolant everywhere. Just last week I lost the radiator hose from the alt pulley cutting it, so ran a little hot. I do not know if they are related or a string of bad luck. After this repair is when I started hearing the "exhaust leak". I don't know if this is when it began or just when I tuned in.

xsboost90

when you pulled into the gas station and your oil pressure dropped, did you check the oil???

inactiveuser92616

Yes. It was a little on the low side but definitely still in the marks. Poured in about a quart and a half when I got home before starting it briefly, it was over the full line then.

Yummybud924

lol, hello Rod.

engine noise can be tricky to diagnose.

Keithr726

Well it may be time to open her up (literally). If you do drive her again make sure to bring your camera and record this noise for us. Knock is said to sound like shaking a can full of coins.

Weston

Yup, sounds like a rod knock (assuming nothing is hitting any of your belts or pulleys), and it may have had something to do with your engine overheating (although that wasn't the entire cause). I've seen several cases of 944 race cars overheating and then developing a rod knock. Overheating coolant = overheating oil = thin oil that doesn't protect very well. Your cooling system issues aren't the cause of the rod knock though... they just accelerated the wear.

A new set of rod bearings is only $60, so get yourself an engine hoist or support then drop the oil pan and swap them out. You can do it in a day if you have everything you need. With any luck, you wont have beaten up your crank journals too much, otherwise you'll need to pull the motor and have some machine work done.

moorepower

Knock, knock...who's there? Rod

That may be the best title ever.

KuHL 951

I hate to be a downer but that final death gasp of spewing coolant is a very bad sign. The rod will be toasted, the crank will need to be turned, and the overheating might have caused hydrolock when the HG went. The bad rod bearing I pulled yesterday was not encouraging at all but at least the HG never went. The rod was bent bad, the bearing was gone, and the crank journal lost some shoulder metal, mine is probably nothing more than anchor material now. This one was shut off at the first knocking sound but it was at 5500 rpm when it went. Low oil level by the PO was to blame. As people will say, anything can be fixed.

FRporscheman

YUK!

I just finished a top-end overhaul and general freshening up of my mom's 968 today (it's been parked for 2 months). And I heard a clicking. I thought it was the lifters still waiting patiently for oil. Then I realized it was more like a ticking, so it must be an exhaust leak. Then later my dad mentioned it sounded like knocking. I really hope he's wrong.

I hope your noise ends up being something less severe as well.

knfeparty

Anyone have a link to a rod bearing replacement how-to? Also, what's the deal with knowing whether or not you need the "oversize" rod bearings also available? I think I saw them on paragon or pelicanparts...if it is as simple as take off the oil pan (are there any obstructions?) then unbolt and replace the rod bearings, then I might consider doing this before anything gets destroyed.
I have had a little bit of metal in my oil before, and definitely had the sudden dip in oil pressure one hot day. What's the easiest way to detect a bad HG? My oil and coolant seem untainted by each other and I have new oil cooler seals.

KuHL 951

I don't think you can use the word "simple" in describing any rod bearing swap. If you are doing it in the car then the biggest obstruction is the cross member that has to come off. Then you get to Chinese Finger Puzzle the pan off of the block as copious amounts of oil drips in your face. Personally I'm too old to do it on my back like that. IMO It's better to drop the motor and do bearings and a reseal on the crankcase or anything else that loves to leak like balance shafts. As far as the condition of the crank and bearings that's better to check with a micrometer. If there are any scratches on the crank rod journal you'll wish you pulled that motor in the first place unless you have Popeye helping you with the crank drop.

yellowline

My 944S parts car did that. I'd let it sit in the yard for a month, and move it once in awhile (I was in school). It would make lifter noise for a good 10 minutes or until the oil was fully warmed. The sound was a knocking sound, but it went away. The engine was full of oil and only had 60k miles.

I think this is a problem with 16V cars- hopefully it's the same with your 968.

CarbonRevo

Ahh, you guys reeeeally scare me with all of these different noises and what not. I don't like it at all!

My S2 makes lots of noises, and some can be traced to lifters/injectors/ and the chain tensioner. What scares me is my new noise when the motor is cold that goes away when warm. I think it's just my balance belt idler pulley because before I tensioned it, the belt didn't touch...now it does. This would explain why the noise is new.

Sorry to hear about this man!

inactiveuser92616

Got the oil drained out, there were some copper colored metal grains remaining in the drain pan. These were about the size of medium-grind pepper, a light sprinkling of them. Another sign that the bearing has left.

greenshoes3

god you have me nervous! my 16 valve ticks as well, but is only noticeable at idle, am i going to spin a bearing?!?