mx5cartalk.com

Hi All,

I'm new to this forum and also to MX5 ownership. I have another classic car and am a regular on a different forum, so am not entirely new altogether.

I thought I would share my recent experience with you all regarding our recent purchase. While I'm sure this has been covered before, it worked for me a treat.

We recently bought a 1995 NA8 in Brillint Black with hard top for our daughter. It is in above average condition with 164 k's.

The idle was erratic at times and other times, after coming to a stop, it would idle high at 2000 rpm for 10 seconds then settle down to 1000 rpm. I also found that after it had been left to idle for a few minutes, the thickest, plumes of smoke would billow from the exhaust. I took it to our mechanic and he told me that if the wrong oil is used in these, that is what it will do. So, 1 x oil change later and away I went.

The problem didn't go away, so back to the mechanic I went. He then changed the PCV hose to a longer piece saying that sometimes that can stop the smoking. Failing that, you will very possibly be needing a new set of rings.

Well, needless to say, it didn't work and I didn't want to go through an engine rebuild.

So, I listed it on Gumtree for sale with the information given to me and that it will possibly need new rings.

During this time I decided to do some more research. The car drove brilliantly and not like one with a problem. While driving normally, it wouldn't blow any smoke at all.

To cut a long story short, I decided to spend the $15 odd and replace the actual PCV valve. I read that if the valve is stuck, it can cause smoke.

So I pulled out the old valve, and what did I find? ...... a straight through pipe. Not quite what a PCV valve should be .....

After changing valves, the idle is perfect with no hunting or erratic behaviour. The smoke has completly disappeared and even under acceleration, It now behaves like I thought it should. Perfectly.

That stupid $20 bit could have cost me $3,000 as I was selling the car cheap based on the smoke problem.

I have now decided to keep the car for the time being. It is a ton of fun to drive and I'm enjoying doing so. As my classic car is not a daily driver, this fits the bill quite well.

So folks ..... see smoke, replace the PCV valve ..... even if you don't think it needs it.

Your mechanic sounds awful.

Surely he would have checked the PCV while he was putting on a longer piece of hose (which in itself is an odd fix)



Checking a PCV is as simple as putting the barbed end in your mouth.
Suck, then blow.

It shoudl let you suck air in, but not let you blow air out.

hks_kansei wrote:Your mechanic sounds awful.

Surely he would have checked the PCV while he was putting on a longer piece of hose (which in itself is an odd fix)



Checking a PCV is as simple as putting the barbed end in your mouth.
Suck, then blow.

It shoudl let you suck air in, but not let you blow air out.

I agree .... it was an easy and inexpensive fix. I suppose the smoke was THAT bad that the logical conclusion was worn rings.

I guess that is the power of the internet and forums like this. It gives poeple with no knowhow, the information and ability to try .....

No, for most mechanics the logical first step is check the PCV valve.

Thanks for this thread. I've been having this smoke issue in my 10AE on cold starts. I'll check the PCV tomorrow.

Guran wrote:Thanks for this thread. I've been having this smoke issue in my 10AE on cold starts. I'll check the PCV tomorrow.

I hope it helps ....

That, after all, was the purpose of me posting my experience. To make others aware that may not be.

manga_blue wrote:No, for most mechanics the logical first step is check the PCV valve.

Yep, my partner is a mechanic, and first step for smoking is to check the PCV or breathers.
Makes sense, the PCV and breathers are a direct pipe from the oily rocker cover to the intake tract.


Jumping to rings first is kind of like going to the doctor with a cough and them saying "well, it's probably lung cancer so you'd best budget for a transplant"
You then go home and have a glass of water and realise it was just a tickle in your throat.

Thanks for sharing a positive outcome.
As I was reading, I also thought your mechanic sounded useless.

Does your daughter get to drive it or is it yours now haha

speed wrote:As I was reading, I also thought your mechanic sounded useless.

Can't help wondering how many people get duped in to paying big $ to supposedly fix their smoky engines - for a 5 minute job to replace a $20 valve ....

speed wrote:Thanks for sharing a positive outcome.
As I was reading, I also thought your mechanic sounded useless.

Does your daughter get to drive it or is it yours now haha

No, she doesn't .... I took it away from her and replaced it after she drove it for a few days and the smoke problem didn't go away.

We were going go sell it cheap with the smokey problem for someone else to fix and have a beautiful car after the repair. I'm glad no one bought it as it would have been a great buy for them, and a lost lot of money for us. It really is in stunning condition.

As you all probably know, they are a ton of fun to drive, and I'm enjoying it at the moment. Will be back up for sale in the next couple months after I'm sure it hasn't got any more problems.

It would probably help to run a high detergent fuel like Shell Vpower or BP Ultimate for a while to clean some of the gunk out.

hks_kansei wrote:Your mechanic sounds awful.

Surely he would have checked the PCV while he was putting on a longer piece of hose (which in itself is an odd fix)



Checking a PCV is as simple as putting the barbed end in your mouth.
Suck, then blow.

It shoudl let you suck air in, but not let you blow air out.

haha you dont even have to go that far. just checking for oil in the pipe between the valve and the intake manifold is enough. i replace a valve once and the pipe dripped oil out of it when disconnected from the valve.

considering his mechanic has already replaced this item, you'd think it would've been checked at time of replacement. this mechanic in question sounds completely useless in so many ways.

manga_blue wrote:It would probably help to run a high detergent fuel like Shell Vpower or BP Ultimate for a while to clean some of the gunk out.

the pipe between the valve and the intake manifold i would remove and clean. if the valve has allowed enough oil through it to make the engine smoke, then it will still have a lot of oil in it.

Thanks for the suggestions folks ....

I did run BP 98 for half a tank after replacing the valve and it didn't seem to like it very much. I'm now running half a tank of BP 95 and it seems to be performing well.

On another note, I didn't put this post up to dis a mechanic. While I understand he didn't catch it, it was posted here to help anyone else that has or is noticing any symptoms of a smoking engine.

A $20 possible cure is worth it in my opinion as opposed to starting to pull an engine apart looking for a possible cure.