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Issue during test drive of 73 88” Series 3

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Posted (edited)

So on Friday I went to look at the 73 series 3 this was the second time I’ve been to look at this and didn't see any major issues.

But while out on a test drive this noise started https://imgur.com/a/Dc3bsTT wasn't there when idling only when accelerating. it was happing in all 4 gears. I was thinking it was more of a transmission issue. 

The owner has done the following “I have gone through the carb, distributor, plugs and wires and cannot get it to run smoothly again. Will check the fuel pump tomorrow. If there is not issue there then next step is waiting 2 weeks for points, coil, wires and plugs to show up and hope that fixes it.”

Then today the owner says “If they don't fix the issue then we have a problem as the only thing left is a skipped timing chain. That only could have happened under a punishing situation such as a massive strain on the engine.” 

I didn’t put it in any “punishing situation” just a test drive on a road. For 10/15 minutes. 

So does this sound like a timing issue? 

Edited by English Canadian
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No, it doesn't sound like a timing issue; that isn't pinking / pre ignition.

As it is happening in all forward gears, but only during acceleration, my thoughts are around the engine + gearbox changing position while delivering torque. First look at the condition of the 4 engine engine / gearbox mounts, then look for polished metal work where the assembly is occasionally touching something.
Check the fan blades aren't touching something (as the engine moves on its mountings).
Do not neglect to examine the exhaust, structure as well as mountings.

The obvious sanity check; has it inadvertently gone into Hi ratio four wheel drive? This might put the front drive shafts (and CV joints) under unusual stress.


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Welcome to the forum,

As above, it sounds like something moving and hitting something else.

Fan and cowl would be first check along with engine/box mounts.


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Why does the owner think it’s not running smoothly? A transmission fault wouldn’t require engine parts to be replaced 🤔

It sounds from what the owner is saying that he’s aware that it’s got an engine fault.

A noise that loud on an engine would only be something serious like the crank knocking under load wouldn’t it?

Difficult to say just from the clip. Hope you identify it.

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Ad David said, it sounds like a vibration contact issue when the engine moves under the torque load.  My money is on the exhaust or the fan contacting the rad shroud.

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I've had layshaft bearings make that noise under load on my old LT77 (happened twice). I would say that's potentially a gearbox issue... I dont know the series boxes but on the LT77 fourth is on the mainshaft and so its a LOT quieter as the layshaft isnt under load the noise was still noticeable when accelerating.

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  • 2 weeks later...

Hi Guys, I really appreciate all the replies,

I haven't spoken to the owner since the test drive.


Today, he sent me a message saying that I had blown the head gasket. It alines with what @Bigj66 said.

 I'll let you know if I hear anything else but it's safe to say I won't be buying this.

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46 minutes ago, Bigj66 said:

Or just offer him a low price and sort the engine out yourself if you’re happy with everything else.

^ this, they're about as simple & repairable as it gets.

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