KV6 engine swap any advice welcome

[stoory70]

Basically,the header says it all,Ive finally found a donor vehicle for my beloved 75 and i'm planning a full engine and gearbox transplant. the donor vehicle is a ZTT estate and my own car is a 75 connoseur.
Please wade in with any hints and wrinkles you can think of. The work will be carried out in the open with minimal facilities.
Many thanks in anticipation

[SD1too]

What's the story Steven? A member for three years and no questions prior to an engine transplant?

Simon

[charlie 22]

Has the gear box gone as well in your 75?. If you put in the gear box from the ztt in you will have a shorter 5th gear. I would personally try and save your original box. On the plus you will get an extra 10bhp out of the box from the 190 engine

[stoory70]

hi. I've had the 75 for a number of years now and it needed a fair bit of work when I got it,basically I rescued it from being weighed in for scrap. Most of the work I've done on the car was fairly bog-standard stuff( springs,brakes ,balljoints clutch etc.) and I basically joined this site to pick your brains. all the problems I've encountered with the 75 are covered somewhere here. A couple of years ago it developed a severe overheating prob,right out of the blue,my guess is that the water pump impeller somehow came loose but on inspection of the oil cap,I found the dreaded Mayo. Looking at the job in hand,I thought that it would be easier to change the engine and refurb the old one while it was out of the car than to attempt it in situ.

[stoory70]

Hi Charlie,gearbox is A-ok so i might just take your advice on that,thanks

[SD1too]

Originally Posted by stoory70

A couple of years ago it developed a severe overheating prob, right out of the blue ...I thought that it would be easier to change the engine and refurb the old one while it was out of the car than to attempt it in situ.

Yipes, I would have to disagree with you there Steve! You need to diagnose the cause of the overheating and that will be very difficult if not impossible when you cannot run the engine.

The most common cause of overheating is loss of one or more radiator fan speeds. Have you checked these?
After that, some V6s have suffered thermostats failing to open. Is your bottom radiator hose hot or cold to the touch?
Another cause of overheating is the mistaken belief that it's a good idea to pour K-seal into the cooling system.
Finally, if the cooling system was drained and refilled without following the MGR procedure (raising the expansion tank included) air locks can be created which cause all sorts of baffling symptoms.

I expect you're thinking that the presence of mayonnaise is indicative of a breached cylinder head gasket. That is, in fact, extremely unlikely on a KV6 and is responsible for many good cars being sent to an early grave. The oil cooler is what you should be looking at because they can and are responsible for the mixing of oil and coolant. The cooler can be temporarily by-passed to help with diagnosis. Alternatively you could remove it for testing.

In short Steve, I think that if it's possible to identify and repair the faults with this engine that would be a much better course of action than removing it and fitting another one which may well give you a new set of unexpected problems.

Simon

[Bolin]

Severe overheating and mayo doesn't sounds good

As Simon says, be sure about the diagnosis before doing a whole heap of work - it is worth checking in case you are lucky. I've had some mayo under the cap before and even on the dipstick, but it was just due to condensation. Obviously depends how much mayo you find

To answer the original question, if the ZT is a 160 then it is a straight swap, if it is a 190 then it will rather more complicated and depend if you would then want to upgrade your Rover to 190 spec - different airbox, different exhaust, different throttle body, different brake calipers (may need bigger wheels), different brake master cylinder, different engine ZCS codes in the ECUs etc.

Not sure if it is less work to remove the old engine and fit another and then fix the old one out of the car rather than just fixing the old one in the car. Depends maybe on how quickly you want the car gong again, quickest option would probably be to swap the whole thing as you plan. Just been going the cambelts and changing the camshafts and other stuff on mine.

[stoory70]

hi Simon and Bolin
, replaced the themostat as a first option(start with the cheap stuff) refilled the system using the correct method and kept an eye on the temp using the OBD display rather than the joke temp guage on the dash. temp stayed steady for a while then just shot upwards. I've got a focus as a runner at the moment,so time isn't really an issue.other than that I never seem to have any,that is. I was talking to a mechanic friend of mine,he said that it was a bit of a bitch of a job anyhow.
I kind of figure that with these cars,there are no simple jobs

[SD1too]

Originally Posted by stoory70

.. replaced the themostat ... refilled the system using the correct method ..

OK Steve, but what about the fan speeds and the K-seal and the oil cooler?

Simon

[Robson Rover Repair]

Id replace everything, and id definitely do what I did, remove heater matrix in cabin, clean it out and flush it all through all pipes to get her 100% clear of gunk.