MX5 trouble...

[DarraghMX5]

Hi all,

Looking for some advice please. Heading to work last week, my 2007 MX5 began to loose power and began chugging. A few days later after having it towed to a garage, I've just been told that I have a problem with cylinder 4 after a compression test revealed its only at 3-4 bar.

The mechanic is extremely genuine and I don't doubt him for a second if I'm honest. He has given two options - 1. Disassemble and send the block to be skimmed and hope that solves the problem or 2. Source a new engine.

What do you think is the best option? Both are coming in at the €1,200 mark. If I wasn't to proceed and just sell the MX5 as is, what would I be looking at price wise? She currently has 195k km with extensive service history and has been babied since I bought her.

Yours,

A seriously disheartened MX5 owner...


Sent from my iPhone using Tapatalk

[Steve]

From what I read on the web :
If you have low compression on one cylinder, pour a little engine oil in the cylinder and repeat the compression test. If the compression improves, worn piston rings are the culprit. If not, the problem is worn valves.
To confirm this is the case, do a leak down test on that cylinder and see if you can detect air escaping via the exhaust side (only true IF the compression rises to a nominal value, IF it only rises a little then it could still be a valve or head gasket).

Also, might be worth giving http://www.traynors.co.uk/ a ring to see what they charge for a used engine.

[MX5Spares]

Well known issues with mk3 engines. Bottom end bearing noises, oil pressure issues and oil burning issues.I can honestly say that I have seen 15/20 cars over the years all with mechanical damage/engine issues . Good used engines fetch 1500e no problem and unless you can see it before it s removed from car you could be buying trouble .Mazda charge just few dollars less than 10k, yes 10k, for new engine ,fitted etc

[DarraghMX5]

Thanks for the replies gents.

Robert, in your experience, am I better trying to source a new engine or is it worth opening it up to see what might be the issue?

Thanks again,

Darragh


Sent from my iPhone using Tapatalk

[MX5Spares]

Buying used engine for one of these can be trouble, and of course you cant be sure it is good.Apparently used ones go for 1500e no problem.

[DarraghMX5]

Buying used engine for one of these can be trouble, and of course you cant be sure it is good.Apparently used ones go for 1500e no problem.

So it appears having done a bit of research, €1,800 supplied and fitted being my best price at the moment. Would you recommend trying to fix it rather than replace then? I brought it home from the garage last evening and when it's idling, there's a steady stream of white smoke firing out the back exhausts.


Sent from my iPhone using Tapatalk

[Steve]

are you thinking of having a shot at it yourself? Change the head gasket and skim the head?
Can't break much more than it is
White smoke sounds like the head gasket, are you using coolant?

[DarraghMX5]

are you thinking of having a shot at it yourself? Change the head gasket and skim the head?
Can't break much more than it is
White smoke sounds like the head gasket, are you using coolant?

Hi Steve,

Ha Christ no, I wouldn't know where to start.

Just popped down to the car there to check and the coolant is perfect, has been at the same level for a long time.

My mechanic has told me that once you go past the head gasket to try and unearth what's causing the misfire, it can be very difficult to put it back together again unless you're a specialist.

I'm caught between a rock and a hard place here because I love the MX5 (stuck driving a crappy 151 rental Corsa now) and still owe a fair bit on the car loan wise, yet don't know if I should be sending it to a specialist or go sourcing a new engine.

Costly whatever route I take I'm afraid..


Sent from my iPhone using Tapatalk

[MX5Spares]

Friend of Steve,s on here had similar issues only his engine was knackered and dealers quoted just less than 10k for NEW engine supplied and fitted !!

[sidewaysreilly]

Firstly,

you need to find out what is causing the lack of compression.
There are 4 possible causes;
1. Cylinder Head Gasket failure. Leak down and Coolant pressure test will reveal a problem. If the mechanic cannot or will not do this, walk away. A good mechanic will have the equipment to do both tests.
2. Ring failure. Unlikely on just one Cylinder. Try to get someone to redo compression test with a small bit of oil poured into the Cylinder. Be careful, too much oil will bend a rod very easily. Turn the engine over by hand first.
3. Burnt Valve or Valve Seat. This will show up as low compression with the oil in cylinder test above.
4. Holed piston....worst scenario.

It is basically a Ford Mondeo engine after all, reworked for Mazda who were forced to use it unfortunately.

[DarraghMX5]

Hi all,

Thanks a million for all of the advice and replies.

It turns out that two of the valves were cracked resulting in the misfire. Fast forward a few weeks and I've just completed a major service costing €1,200 which included head gasket, exhaust gasket set, new timing chain, tensioner, exhaust valve cylinder, new valves, 16 valve seals, oil and filters.

The MX5 is good as new now and ready for road. Unfortunately the repair bill has come at a bad time, so I'm going to have to bid farewell to my beloved mk3 which is easily the best car I've owned.

All that is well unfortunately doesn't always end well.

Darragh.


Sent from my iPhone using Tapatalk

[leamyj]