mx5cartalk.com

Hi guys,
so my daughters '90 1.6 has clocked over 400k and she commented that it's been running rough.
So I have a listen and almost cry. First thought, head gasket, but no oil in water or vice versa.
Compression is 175, 170, 110, 175. So likely a Valve.
Its the original motor with a SNC. Is it worth rebuilding?

We have at our disposal a '98 JDM 1.6 with a BNC, with around 150k on it, but unsure of its quality, it was already removed from the donor and was cheap
PO said it was fine, Timing belt was done 20K ago, and I've no reason not to trust him.
So the short term plan is to drop the replacement in, The car is her DD so can't be off the road for long.
What should I check on the replacement before dropping it in. It looks ok, as in no leaks or wet areas and hasn't been steam cleaned to hide anything.

Replace, it's a better engine and more cost effective.


Sent from my iPhone using Tapatalk

engine replacement can be done in 1 day. You just have to find someone who has the time to do it in that time. Or willing to work only on 1 car for the day.
The engines are pretty strong.
I put in a JDM engine which had 40k km in production sports.plus about 30-40 k km in Japan before it started being used as a race car here in AU. Now thats heavy use. I put that engine in 10 years ago. Its still going strong. Its done 120k km since then.
In my case I know it was looked after while it was raced here in Australia. Its been looked after by me for the most part since it got transplanted into patchy.
It uses a little oil now. But that's it. Not surprising though.

a total rebuild might cost you $4-5 K if not more. It will not be as good as an engine that's come from the factory. The B6 motors can be trashed (err.... dríven hard) for a long time. Mine is a prime example of this. Patchy has been raped & pillaged. The only problem is if previous owners don't change the oil or let it overheat too often. Its a little gamble. a worthwhile one in my opinion.

Wont you need a loom ecu new intake pipe modified fuel system etc?

NitroDann wrote:Wont you need a loom ecu new intake pipe modified fuel system etc?

I don't think so
Shouldn't it be a straight swap as they are both 1.6L. No VICS or VVT involved, even has the return line on the fuel rail/fp regulator.
It was running in a 91 NA prior to removal.

Remove and refit will be done at home, I'm semi capable at parts replacement just don't ask me to actually fix broken stuff.

If you want to retain the car then engine replacement is the go. Repairing engines is expensive. Maybe consider if a replacement car makes longer term sense.

Mr Morlock wrote:If you want to retain the car then engine replacement is the go. Repairing engines is expensive. Maybe consider if a replacement car makes longer term sense.

That would be practical, but she's young, it's her first car and she is still in love with it - it's an MX5, what's not to love .
The rest of the car is actually in good nick considering the 400k that it has done.
Dropping another engine in is the current plan and will probably see out the rest of the life of the car.
She's doing this on a Uni student budget too, so expensive rebuild is out of the question.

I'll keep you posted on how we go, not happening this weekend though.

Ross wrote:'90 1.6...
We have at our disposal a '98 JDM 1.6

1998 would make it an NB6 B6 motor - has been done, but worth some research to see if it's a straight drop in or if you need to do some mixing & matching of peripherals (the latter from memory).

Following gives you an idea of what you'll need to do:
viewtopic.php?f=29&t=46526
Use following for further research as Forum search is limited:
https://www.google.com.au/#q=nb6+site:h ... artalk.com

The cam/crank angle sensor needs to be addressed, as the nb6 motor runs the nb style sensor.
Have a search for omgpham's engine swap, he went dropped an nb6 motor into an na6, as well as some other little bits and pieces...

Sent from my LG-H815 using Tapatalk

From what i can see, it's been converted to run in a NA already. It was running in a NA previously.
The alternator is still attached and is a V belt and the CAS is on the back of the intake cam. The inlet manifold is there but no TB.
Anywho, we'll give it a wash down, pull the dying NA6 and then put them side by side. Anything that doesn't look the same, I'll pull from the dead one and put on the good one
Sounds simple, right

Replacement went in yesterday, went pretty well, seems to run OK, haven't road tested it yet as I forgot to get some brake fluid to bleed the clutch line.
Not looking forward to that, have read all the horror stories on miat.net. Probably should have changed it to a straight braided line and got rid of the pig tail, but as I said before, uni budget and time is cheap.
Everything just connected up as per the old motor.
The new newer B6 still has HLAs.

Her first engine removal She always helps with any work we do on the car, she's not a "daddy, fix my car type", more of a " help me fix my car type".
https://drive.google.com/open?id=0BwO6FyRfsz-xbVppdEY4WE0wS3M

Thanks, Ross, for posting this - useful info for me to tuck away for some future day with my NA6 (now at almost 300k). Great daddy/daughter project too!

From memory...

The NB6 engine has shim over bucket. The head casting is the same but the camshaft on the NB6 is missing the cam drive. In order to retain the valvetrain from the NB6, the camshaft must have the CAS drive adapted. The NA6 camshaft can be cut, and a machinest who has done this before modifies and roll pins said drive onto the back of the NB6 camshaft.

If your engine has HLA's, then the lifters and camshafts have been swapped to your engine.

I'm not 100% sure but I'm 95% sure the camshafts in the NB6 engine are slightly more aggressive when compared to NA6 items.

I could be wrong...

Minor setback - waterpump is leaking - badly
So WP and TB replacement, the old motor was overdue anyway so had to be done at some stage