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Discussion summary
YOUR RESEARCHWhat could knocking mean in an FS ad?
Reported or suspected cause
minor problems
Reported cause
No successful repair reported for this finding.
1
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0
Suspected cause
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Read evidence and context
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Discussions that report identifying a cause
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Reported cause
There are more instances of cars with problems being sold in which the problems turn out to be deeper, more serious than the buyer suspected than there are cars sold with what proved to be minor problems.
Leading evidence: 'minor problems' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'minor problems' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Run away' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Saw a cheap car that advertised the engine ran but knocked.
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Suggestion
There is a chance, if the car's been parked a while, that the knocking is lifter noise that will go away after the car has been run for a few miles.
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minor problems
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
There are more instances of cars with problems being sold in which the problems turn out to be deeper, more serious than the buyer suspected than there are cars sold with what proved to be minor problems.
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12 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
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Generation: 20261026T142254Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Saw a cheap car that advertised the engine ran but knocked. Gathering opinions on how bad and how easy it could be? I know PPI but am curious what you guys think? Worse case is that it needs a new engine at $16,000?? Top end rebuild for $10,000? What else could it be?
if you ask your local porsche service center, they'll advise you that it's not uncommon for the engines to knock. i wouldn't be overly concerned about just the knocking part, but would make sure to get the entire package checked out.
beware: you get what you pay for. why buy a "cheap car" 911? good luck!
the 996 engine is quite noisy, a lot of chain noises and clicks, but knocking.. I'd be concerned.
loud clicking may be...
PPI will be useless for this, Porsche will most likely tell you it is nothing then wait for you to come back and give you a big slap in the face with a $3k bill...
At least with clean ppi you can get into extended warranty and fix it under warranty saying the car was fine when you purchased it
Timing problem. Time to run away.
Unless car given to you you are better of giving the car a miss.
Sure, it could be something minor but suspect it is not or the seller would not be selling the car.
There are more instances of cars with problems being sold in which the problems turn out to be deeper, more serious than the buyer suspected than there are cars sold with what proved to be minor problems.
If you want to proceed....
If the car checks out fine otherwise, then budget for worse case scenario: New engine needed; and price one -- get firm quote -- sourced from dealer and installed by dealer to get 2 year, 24K mile warranty.
Better budget another 10% of this cost for incidentals that will almost certainly turn up: coolant hoses need to be replaced or u-joints or half shafts or bad converter or o2 sensors, etc.
Just set aside 10%.
Then subtract cost of new engine and that 10% number from the car's market value as best you can determine the market value which would around what the car should sell for assuming the car didn't have a potentially very expensive engine problem staring a buyer in the face.
You can't use the seller's asking price cause he's not factored in the worst posisble scenaro cause he's letting you believe it is not *that* bad. Your attitude is helping him sell you the car.
Even if he's factored in something, he's not factored in enough. Not nearly enough. Would you if the roles were reversed?
Anyhow, what number you arrive at, this is the car's value but this assumes you did a good job appraising the car's condition and ascertaing the market value of the car. Remember too your focus is on the engine. There's plenty of car besides the engine to look over, check out, and consider before leaping.
My opinion without having seen the car, is essentially the car is near enough to a non-runner to warrant hardly much more money than a non-runner would go for.
You have the time/effort to get the car fixed, and then once fixed sort out any other issues that arise, come up, as they almost always do.
If you get the car at a good price then you can spend some money to find out what's wrong. If it proves to be something relatively minor then you did well, got lucky. You want to be careful that you don't sink too much money into digging into what's wrong. At some point you may have to toss in the towel and get the new engine installed. Since you got the car with this cost already priced in or out of the car's market price this shouldn't be an action to fear.
It is after all what you assumed going into the deal.
Odds are high though you'll need every penny of what you didn't pay for the car to get the car on the road in a condition that makes owning and driving the car a pleasure, not an on-going regret.
Sincerely,
Macster.
If it is rod knock then whoaa. Some guys refer to knocking when an engine detonates. I'd defer to Macsters post in any case. Why sell the car if it detonates/knocks? Why would it do this if all the electrics were working fine? It shouldn't detonate/knock even with bad gas. If it is the big end going south then you need a new engine sooner than later. If it is a screaming deal and it really is just detonating then factor in what it is gonna cost to sort that out if you do the work or take it to a stealer. The variocam bits aren't cheap and the labor is intensive.
Of course your mileage may vary. Best of luck!
Would be nice to know an undiluted history. Like age of fuel, length and times stored away like it was a cheese to rott more. Best thing to do to eliminate the cracked rod chance is take it out for a test drive and rag it out. If it is a cracked rod then it will turn into a thrown rod and piston. Easiest way to find out
Experience teaches all except for on the internet
The one thing I don't like is the way premium fuels just don't go very high in octane anymore at least in hawaii. Knocking is something you can feel in the seat of your pants. If there were higher than common 92 octane around then going to a higher octane would work well to diagnose and eliminate the fuel ocatane as the source.
OK some times guys will get the sputtering of under load and say it is knocking. Best to be in the car or around when the knocking is going on. If it is while parked then really not good. But anyway long story short. If it has the sound of vlavles floating and clinking its a good chance it mainly weak valve springs. Don't calculate price off for valve springs job because springs that go bad in the form of more than one to be sold as knocking is from heat exposure of the bad kind. This isn't just trashing springs but scoring pistons, rings, cyclinders, valves and frying the same. Common is breaking of piston rings. Knowing the history once again would be nice.
Tough times looking at a car you haven't owned since new. One reason buing new is the best route.
There is a chance, if the car's been parked a while, that the knocking is lifter noise that will go away after the car has been run for a few miles. It's also a possibility that it could be a driven accessory, air pump, alternator, air con compressor or other. In that case the car could be a steal.
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