15 replies to this topic

[Chris Thompson]

I'm not a spec miata racer but you guys know these motors better than anyone. My 99 has a cold start rattle for 2-3 seconds then seems to be just fine. It's really a rattle not a knock. Would that likely be rods, loose piston skirts or something else? I suppose I know it's rods because it's quiet after it builds oil pressure but thought I'd ask anyway. I autocross it most every other weekend. Hits the rev limiter a couple times most events. No complaints from the motor except on cold start. How long do I have before she goes boom doctor? Should I park it now and yank the motor or just keep hammering it?

Thanks Y'all!

[Jim Drago]

It sure sounds like a rod.. You can put some 20/50 in it and cross fingers or address problem now when it is still relatively inexpensive, it will only get worse.

[Chris Thompson]

Thanks Jim. I think I'll yank it out now and start autocrossing momma's 08 NC till the NB gets healed up. Are all the 1.8 blocks the same or are the bucket/shim ones different?

[Chris Thompson]

May be a blockage at the pump pickup or a weak pump. I put 20-50 GTX and a bottle of STP just for good measure. Sounded good while it was warm but stone cold this morning it rattled WAY worse and longer and I shut it down. Any advice for best way to get a long block? Local machine shops in San Diego are hit and miss on quality.

[Glenn]

May be a blockage at the pump pickup or a weak pump. I put 20-50 GTX and a bottle of STP just for good measure. Sounded good while it was warm but stone cold this morning it rattled WAY worse and longer and I shut it down. Any advice for best way to get a long block? Local machine shops in San Diego are hit and miss on quality.

Mazda Crate.....

[Chris Thompson]

Mazda Crate.....

I thought crate motors were no longer available? That would be my first choice. I saw they had chin spoilers listed the other day. I need a new one of those too! I'll ring them up. Thanks Glenn.

[Glenn]

I thought crate motors were no longer available? That would be my first choice. I saw they had chin spoilers listed the other day. I need a new one of those too! I'll ring them up. Thanks Glenn.

MAke sure you are a Mazdaspeed member too to get the best price.

[Mike Collins]

The 99 crate is no longer available. Id bet big $$$ its the number 4 rod bearing.

[Brendan O]

The 99 crate is no longer available. Id bet big $$$ its the number 4 rod bearing.

This happened to me on my stock 92K 2003 1.8L last weekend at a Barber track day:

http://www.youtube.com/watch?v=QD5JMCPk07Q

I also had the cold start rattle of "impending doom". We think it was #4 rod bearing. But my question is: is there a "known" problem with #4 rod bearing on the 1.8L longblock? Why is #4 more likely than #1 thru #3? I guess I should do a search.

I have decided to go with a new crate. Does Mazda make them? Or is it KIA etc?

thanks
Brendan

[Keith Novak]

It's farthest from the radiator inlet so it gets the hottest.

[Brendan O]

thanks - does that mean it is the weakest and most likely to deform in the case of an over-rev?

[DES4]

It's farthest from the radiator inlet so it gets the hottest.

I'd have guessed because it's the furthest from the oil pump; in the event of oil starvation/plugged passages, #4 would be the most impacted, yes?

[Chris Thompson]

That sucks Brendan. My guess would be farthest from oil pump...lack of pressure, not cooling. Perhaps there's an engineering weakness? I haven't rebuilt mine yet. Too busy at work to have a life. Robello seems to be the popular So.Cal motor builder. Anyone wanna toss out another name of a known trustworthy shop in So.Cal? I don't need to conform to spec rules.

[Keith Novak]

Higher temps = weaker metal so it is the most likely to deform when you over rev it. It also releases the tension on the bolts so they're more likely to loosen up and/or cause bits to bang into each other more than they should.

[Brendan O]

ok - thanks - once i pull the engine and take it apart, i'll post some pics.

How long should a new 1.8 VVT crate last if i'm careful and don't over-rev? Is it a JDM engine or does South Korea (KIA etc) build it for Mazda?

[Chris Thompson]

I'm back to give y'all an update so you can learn from my misfortune.

My 99 lived without a rebuild. Turns out I had a bad WIX 51365 oil filter. Strange thing is as soon as this noise began I pulled the VDO/TDR sender and checked the oil pressure with a mechanical gauge. Pressure was fine...it seemed (25psi idle, 55psi at 3000rpm). Was all ready to replace the motor with a low mileage '05 VVT and DIY Controller when I stopped and thought I'd just check one more thing. Changed out the filter for a WIX 51356 which is the same filter specs only ~3/4" taller. 10-40 dino oil and no more cold start rattle. I drained the bad filter and compared it with several more of the same filter...manufacturing defect for sure in the spring assembly. The bad one is not even close to the same as a known good filter inside.

I have no idea what the defect was causing to happen. I suppose it was starving the motor of oil pressure for a few seconds when it was cold or leaking down or? Whatever it was, not cool! Can I sue WIX or something for possible damage? Arrrrg!

I don't suppose Brendan O got off so lucky?

Always look carefully inside and compare some filters before risking a motor.