All the guides I’ve seen appear to remove the engine with gearbox attached. To save the faff of having to undo everything associated with the transmission is it possible to remove and replace the engine on its own?
Some debate either way but nobody I know would leave the gearbox in place.
Here is a thread that debates this…
https://forum.miata.net/vb/showthread.php?t=494053
Are you proposing to do this yourself? - big job for a non mechanic if you are.
It’s certainly possible to do both in a Mk1 as I recently did it both ways. If you keep the gearbox attached you just need to get the front of the car high enough to clear the tail of the gearbox. Removing the engine separately requires the dropping of the front anti roll bar to allow the engine to pull forward off the gearbox. I found removing the top starter bolt awkward but it’s reasonably straight forward either way.
I am a dab hand at mechanics - fully rebuilt my TVR wheels up and do all the work on my bikes and the old hack Vectra so able to face most jobs. I have a pit and overhead hoist in my garage (sadly poor planning means the hoist isn’t over the pit) and access to an engine hoist and 2 or 4-post lift at the works motor club if I need it. I always take the TVR engine out without the gearbox but then its a simple old beast. Only concern is the PPF and whether that has to come out or just be detached at the front.
Removbe gearbox ,wiring at gearbox, speedo cable and front of PPF frame and lift the gearbox and engine out together. It is possible to remove engine on its own as above but awkward to get bellhousing bolts back in and tightened and also some have brackets/starter attached etc
OK, job done and the car is a real sweetie. Having lost confidence in the car my daughter bought a lovely Mk4 Sport Nav and let me have the 2.5 for £500 which is pretty much what it was worth with the duff engine. Spent £300 on a 39k engine, and £60 on gaskets, studs, antifreeze, oil and filter and find myself with a pretty tidy 69k 05 plater.
Did the engine change at home on my own with the gearbox in place using ramps and a borrowed engine lift and here are my thoughts:
Pros:
All my tools readily available
Easy to work in small chunks
No need to drain gearbox, remove prop shaft etc
The wiring is really straightforward as Mazda have cleverly used different plugs where there is any risk of getting thing in the wrong place. Only thing to remember really is which wire goes to the starter solenoid and which to what I think is probably the oil pressure switch.
Cons:
Limited space underneath so it would have been an easier job on the motor club 2 post lift but would have to work non-stop to minimize hogging the lift
The gearbox bolts are accessible with a suitable selection of extension bars but very tight with limited leverage to undo them
Engine and gearbox need to be raised as far as possible to allow engine to clear the x-member
If exhaust can’t be released from support bracket bracket on bell housing the centre section with cat can’t be removed until engine/gearbox is raised
There is a lot crammed into a small space - a small handed gynaecologist would make an excellent assistant!
The engine is a long way back and a lift with a long arm is needed
To get the right angle to marry the engine to gear box on reassembly a balance bar is a must - don’t know how I’ve managed on the TVR for so long without one (bar using brute force to hold the engine at an an angle)
The engine mount studs go through a hole in the subframe at the nearside and a slot at the offside. The nearside stud needs to go in the hole first but because the gearbox is fixed fore/aft by the PPF I found the only way to get it in was to put a little weight on the stud roughly lined up with the hole and then give it a whack towards the hole using a long screwdriver so it dropped into place
The fuel pipes have a quick fit connector to the throttle body and filter and are definitely not quick release without the special tool or home made equivalent. Screwdrivers might work but risk damaging both the fitting and the pipe.
I did the whole thing without reference to a manual and it was frustrating at times but relatively straightforward - an assistant would have been useful for a couple of things. I pondered doing a cam belt and water pump change before fitting but decided against it as the engine had a 30 day warranty and I was assured it was a good runner before being removed and didn’t want them to have any reason to renege on the warranty. Would I do it again? Probably yes for myself as I’ve ended up with a £2000 car for £850. Would I do it for someone else Well it’s a lot of work so probably not unless they were willing to make a contribution to my petrol (MX5 fun) fund!
Hi,
I have also just changed the engine only on my 1.8 Mk1 and have to agree with many of the comments in the above post. I had help with the actual lifting out of the engine and re-installing the replacement, but was able to finish everything off myself. Rod Grainger’s enthusiasts workshop manual does include the engine only removal and replacement procedure. Not a job I would want to do again in a hurry, but glad I’ve done it. Just taken the car over to Ireland for a holiday and the new engine ran perfectly.
Nigel