Test drive for potential buyers

[Superbracey]

As a seller I wouldn't want the prospective buyer to 'rag' the engine, particularly if they werent serious about buying it. But I can understand they might want to check the engine that way.

A buyer may want ti check if the car bellows thick smoke above 3k rpm and is potentially going to fail an MOT on emissions. So I would grin and bare it for the sake of a potential sale, once or twice. Not constantly ragging it though.

I just bought a 2.4 d24 engined 940 and wouldn't want to rev it too much. On the test drive I was allowed to get the engine nice and warm and I put my foot down to check it accelerated ok (it's an auto so I wasn't red lining it).

In December I bought a Corolla T-Sport, a 1.8 litre N/A petrol car that produces 192bhp and revs to 8,500. It's the polar opposite to my Volvo. It is recommended to check any prospective T-Sport purchases rev cleanly past 6,200, where the cam profile changes and the power picks up. The seller (a dealer) was a bit of an arse and didn't want me to rev the car at all durine the test drive. I said he mus be trying to hide something. It took a lot of arguing that I was testing a car designed to rev to nearly 9k and which would show a known fault if it wouldn't change cam profile at 6,200 rpm. He didn't want me to break the engine, I didn't want to buy a lemon.

He relented, the car revved well once thoroughly warmed up, I bought the car. But I nearly walked away from the sale.

[searider]

I've just sold a remapped Audi S4 - 330hp and once warmed up fully encouraged the buyer to put his foot down. I had every confidence in the car.
Similarly I test drove a BMW 550 which showed an irritating at "high" motorway speeds - again encouraged by the seller.
The 186000 mile V70 D5 I just bought as a stopgap car I was taken on a test route that enabled me to fully test the car including some high rpm periods.
All was ok so I bought the car.
Redlining a Diesel engine won't damage it.

As an aside as part of my work I sea trial boats. Part of the sea trial is to run the engine at full throttle, full load, for 5 minutes and observe what happens. Without doing this you can't determine if the engine is healthy.
If it overheats - problem
If the oil pressure drops - problem
Smoke - problem
Vibration - problem
95% of the time no problems.

Volvo supply marine versions of the D5 with 160hp and 190hp and all can stand running at wide open throttle for 5 minutes or more. This is the same as running down the motorway ( Autobahn!) in top gear with your foot flat to the floor.

So no need to worry about engine damage on a road test - unless you have something to worry about..........

[skyship007]

One big thing to check for with all engines is oil leaks. If it's a cam shaft oil seal, it's best done when the cam belt service is due. A main output bearing means removing the gearbox etc. Another common one that can be bad news is a turbo oil seal issue, as it tends to indicate the bearing is kaput.