Incorrect timing belt install + timing

Technical Area Engine, Transmission, Exhaust etc
2

Hi all, new to the forum, I made a mistake the other day when replacing the timing belt on my 1998 MX5 MK2 1.8 which was the fact i forgot to crank the engine over by hand to top dead centre before replacing the timing belt. This means the engine timing is off and therefore the car isnt starting because of it, however because i have the MK2 ive read that you cant manually change the timing like you can on the mk1. Instead the ECU controls the timing of the engine for you and theres no way to adjust it. So my question is how do i adjust the timing so i can start my car?

Thanks in advance 

Harry

3

There are no adjustments you can make to fix this. You need to remove the timing belt again and reinstall it with the crankshaft and camshafts in their correct TDC positions.

4

If the belt in fitted incorrectly it has to be removed/refitted.If you are familiar with cars etc it is possible to just remove belt off top pulleys whilst leaving bottom crank area still assembled.Saves lot extra work .
Remove cam cover, front top 2 timing belt covers etc but leave bottom cover/crank pulley etc in place.You can then see the timing marks by looking down behind the bottom cover etc

5

Morning Robbie, thought it was only me up this early!!

6

OK thankyou for your advice guys! I don’t mind reinstalling the whole belt again I just want to get it right this time. So if I get the engine to top dead centre before I start, and then reinstall the belt as usual like I did the first time does the timing go back to normal? Or will I need to correct the timing when the belt is off?

Thanks 

7

You are getting very confused.

Getting the cams and crankshaft in the correct position corrects the valve timing.

The ignition timing and for that matter the fuel injection timing is also a function of what the sensors on the engine pick up when the camshaft and crankshaft are in certain positions.

You as a user cannot change the ignition and fuel injection timing as they are controlled by the position of the crankshaft and camshaft via the camshaft and crankshaft sensors.

8

OK great thanks for clearing that up for me! I’m still unsure on how to get the  cams and the crankshaft in the correct position to correct the timing… 

9

Harry

all three pulleys - exhaust cam, inlet cam and crank need to be in the correct positions.

Crank is easy to set with marks but cams need holding in position - I used a pair of big adjustables on the camshaft hex sections and clamped them together.

There are lots of ‘how to’ instructions online to assist with this job that will explain this process fully

This makes it look very easy…

https://www.youtube.com/watch?v=pOOUIwSlF8A

   

 

10

That video I think clears it all up for me thankyou very much! So if I crank the engine to top dead centre I can then hold the cams in position and there’s no need to adjust them? Then it would be the case of adjusting the crankshaft until it hits the mark?

Thanks

11

I have now removed all the timing belt covers and any pulleys in the way to get access to the belt. The belt is still on with all the pulleys and I have cranked the engine to top dead centre. Now I’m not sure what to do from here to get the timing correct, can anyone advise?

Much appreciated 

Harry

12

With the crankshaft on TDC, check that the camshaft pulleys line up correctly with the E and the I marks? If not, you need to remove the timing belt again and refit it with the camshafts correctly lined up.

13

OK perfect thankyou very much everything cleared up for me now! 

14

Cambelt changing is a bit daunting but if you understand the principles its quite straightforward really.  Unless you have a vernier pulley on the crank and ignoring the VVT variations all the timing is fixed and dictated by the position of the camshafts on the toothed belt in relation to the crankshaft.

In your case turn the engine by hand so the crankshaft marker lines up at TDC - mark it with a bit of white paint or tippex and taking out the spark plugs makes it easier.  Loosen the tensioner and take the belt off.  Turn the camshafts to line up the I and E marks on the block and toothed pulleys and lock them with a couple of big spanners and a clamp.  Ignore the white marks on the attached pics - look for the small triangles by the I and E on the pulleys.  Refit the cambelt making sure there is as little slack as possible on the side that doesn’t have the tensioner and then adjust the tensioner as per the manual.  Having turned the engine over by hand a few times you should be able to check it’s correct by getting it to TDC on the crankshaft marker and checking the timing marks still line up (it will be on every other rotation).  Don’t be surprised if it not absolutely perfect but it should be within 1 tooth.

 

Hope these pictures help.

http://www.perrywinkle.co.uk/cambelt7.jpg

https://www.miata.net/garage/holdcams.jpg

 

15

This is a great step by step thanks very much! Very clear too so hopefully it should go smoothly today! 

16

Engine is now running perfectly, thanks everyone for the help!

17

Well done - easy when you know how isn’t it.

 

18

And with good instructions!

19

Not sure if it’s mentioned in an earlier post but if you edit your profile and add your location - general area if you are shy  - you might find there are folk nearby who’d be willing to assist either hands on or by having a quick look-see at what you are doing or have problems with, or know a good local fixer!

20

Will do!