AJP Reliability

[mjf93]

Hi all,

I am starting this post to pool some information, for myself, I am aware that there are a few previous threads on the subject, but I wanted to clarify a few key points to myself.

There seems to be a great difference of opinion with regard to the reliability of the AJP units, with a lot of people claiming bulletproof reliability, and others reporting weak cranks, head gasket failures and various other failures.

For the purposes of this thread, I would prefer to stick to the V8 variants, both 4.2 and 4.5.

I am fully aware that there is no set criteria for engine failure, and that maintainence and machanical sympathy play a large part.

A lot of information I have read regarding the 4.2 engines seems to indicate that the early cars were the only ones to suffer from crankshaft failure, 96-97, is this correct? If so, what changed after 97, and how can the changeover point be determined.

I have read a lot of information which claims the 4.5 to be considerably stronger, why is this, and can the 4.2 be modified to this spec without an engine swap? Are the head gaskets stronger on 4.5's also?

Any other differences or points of discussion are welcome.

Thanks, Mark

[mjf93]

Thank you all for the replies. Very helpful information.

So to clarify, do the later 4.2 AJP cars have the larger crank journal size, as the 4.5, or are they simply made of a stronger material.

Head gaskets sound like something which may need attention on all variants then. As I understand, this problem is exacerbated by infrequent coolant changes. Is this correct?

I have also read, in various places, that the top end can be damaged by not having the valve clearances checked, a 12k service item I believe, is this you guys experience also? Is this also a time related service item, or just mileage?

Steve_T said:

What changed from 4.2 to 4.5 (aside from bore and stroke) was crank journal size from 2.3 inches to 2.5.

Steve, from your profile, I believe it was yourself that I met at the Classic Le Mans, and took me for a spin. Thank you once again for the ride in your beautiful cerb, and helpful information.

[mjf93]

gruffalo said:

In the 50k miles I have covered in mine I have not had a single mechanical failure with the engine. The head gaskets did start to weep coolant up the head bolts but that was an age related issue with the gaskets rotting after 18 years of service.

I have had a couple of issues with the gearbox but to be honest I do spank the old girl regularly, the engine seems to love it but the gearbox has complained about it twice.

A few electrical niggles like earthing issues and one set of clutch seals but only the gearbox has actually left me stranded.

Are they bullet proof, in my opinion yes they are with the provision that they are properly maintained.

If you can make it to Brands Hatch on Monday you can hop in for some pax rides, that should sell you on the engine:-)

Edited by gruffalo on Friday 15th July 14:00

Thank you very much for the insight and your offer. Sadly, I won't be at Brands on Monday to take up your offer, but if you get any videos from the day I would love to have a watch!

I guess my biggest reservation is I am coming from a GM production car, a Monaro, into a much more bespoke machine. Whilst that is a large part of the attraction, I need to know I could trust it to head down to Le Mans, or other road trips, on a yearly basis without catastrophe.