Help: Fuel smell in engine oil

[Steve_SK]

Dear friends,

after the first positive impressions with freshly rebuilt engine I am experiencing more and more problems and I am thinking of getting rid of this MX-3 crap, really. I am so upset.. and sad.

So what happened?

I completely rebuilt engine in summer, new rings, HLA set, gaskets all around, rebuilt heads (cost 700 euro for both) etc. etc. And the news...after 700 km of running rebuilt engine 0,5 litre of oil is gone, plus I can smell fuel in the oil. After startup in the morning the smoke coming from the back of the car is a little bit dark grey, disappears after 20-30 seconds and there's only ordinary white smoke as it should be.

I have no idea what's wrong again with this crap, please help, advice, anything .. before I drive the car on a junkyard.

Thank you.

Steve

[Ryan]

fresh engines will consume more oil as the rings break in.

I suggest checking your compression, and if that checks out okay, pull off the intake manifold and see if there is oil laying on the valves. Valve stem seals only mask a valve guide clearance issue.

[Inodoro Pereyra]

Steve:

First, +1 to what Ryan said.

Second, you can't blame the car for what can be, worst case scenario, a bad rebuild. People seems to think that replacing your rings, seals and gaskets is the solution to all their problems. Well, sometimes it is, sometimes it isn't.
Did you check your valve stem clearances? Did you measure your pistons and cylinders, to make sure they're round, and within specs?

If you didn't (and chances are, you didn't) you ma actually be making the problem worse than before.

First, change your oil. My schedule for oil changing after a rebuild is 500 miles, 1000 miles later, and 1500 miles later. I know many may consider it overkill, but, IMO, it's cheap insurance against loose shavings going where they're not supposed to.
Then, keep on running the engine. If after another 500-1000 miles it's still smoking, it may be time for another, more serious rebuild.

[Steve_SK]

Friends,

I know newly rebuilt engines take more oil, I am just confused and worried.

This is my fourth engine rebuild (second of this engine). I rebuilt engine on my sister's Astina 323F in summer 2010 in one day and the engine runs like new, only took 0,2 litres of oil and since then no more oil burning.

Of course I measured everything, cylinders, pistons, piston pins, crankshaft, camshafts, my heads were profesionally repaired with new valve stems, seals, everything measured, pressure tests, cleaning.. (more in my worklog with pics). I used genuine Japanese gaskets (nippon) and NPR piston rings (I have excellent experiences with these on all my mazda cars) and they were installed correctly on clean pistons and their grooves. All in all I know the rebuilt was done perfectly.

I will do a compression test soon and will see. I also have a new disty cap, rotor, spark plugs, PCV valve & gromet etc., but:

1. I haven't exchanged spark plug wires
2. I am not sure about O2 sensors (there's no error code in memory, checked yesterday)
3. I am going to exchange fuel pressure regulator, because the car starts after long time (6-8 seconds) and sometimes when it is hot it starts slowly from 700 rpm to 1500 rpm and then slowly down back to 700. I am used to start the mazda car on 2-3 cranks and dirctly to let's say 1500 rpm and then back to idle when the engine is hot. So maybe that's the problem.

After these steps there's nothing more I can exchange.. Everything is new there.

[Savin]

1. I haven't exchanged spark plug wires
3. I am going to exchange fuel pressure regulator, because the car starts after long time (6-8 seconds) and sometimes when it is hot it starts slowly from 700 rpm to 1500 rpm and then slowly down back to 700.

Change spark plug wires. And get fresh plugs too since its burning oil. That 6-8 second crank time is dumping extra fuel in the cylinders which is probably seeping back down into the crank case. FPR can cause this too, along with leaky injectors. (simple stuff)

Lastly, as Inodoro stated, change your oil. Gas in oil is baaaaaaad.