Mirage 3A92 Engine repair in process. (Problem: low compression)

[DirtGearTv]

Mechanic-

it’s .0010 but unlike many manufacturers they are not using a oil passage on the BE bearings. So that thick oil is going to have a hard time getting through those rod end bearings IMO

[Mechanic]

Dirt,
. . . . 1 thousand is on the tight side and it is especially troublesome with no oil groove. My 323 and Protégé both have 1.5 thousands on the bearings and they run with oil grooves. But my other engine didn't have a bearing failure. The cylinder walls went a way. You build high performance Mirage engines don't you?
GOD Bless and Thanks,
rich!

[7milesout]

I'm an engineer. A mechanical engineer. That's not to say I'm an expert. I'm really not an expert at anything. But holding a patent with Toyota, Hyundai, and 2 of my more recent employers, I think I'm maybe smarter than average. A patent doesn't prove intelligence directly. Timing and needs have something to do with it too. That said, I'm just saying that I'm not trying to thump my chest here, but that I don't drool into a cup and walk around dragging my knuckles either.

It's been my experience (trying to forget the Hyundai experience, that was a joke) with Toyota, that the engineers beat themselves silly to get things right. They are not perfect. And Toyota's general attitude in the cars they develop is to make a customer happy. No joke, that's what they want. If a car has problems, customers are not happy. If they are happy with their Toyota, they are likely to buy another, and influence their neighbor to buy one.

And with that said, I have to believe the oil viscosity recommendations are based on research, with endurance testing results. Rich you drive your Mirages hard. Even my little bit of mostly empty trailer towing pales in comparison with what you have done. Personally I would stick to what the manufacturer suggests. What's going on inside our engines is WWIII, and is very complex. There could be a myriad of reasons you had an engine problem or two with Mirages in the past. And it could have NOTHING to do with the oil at all. Things are complex. In any event, I'd stick to what the manufacturer recommends. I have been part of the "machine" that designs / develops / manufactures automobiles. And there's more to the viscosity recommendation than just mpg savings.

[DirtGearTv]

Dirt,
You build high performance Mirage engines don't you?

I don’t know that i’d go that far, mostly I blow them up “for research purposes”

[AtomicPunk]

Dirt,
. . . . Because all of my education, training, and experience tell me that a 50 weight oil at 200F provides better bearing protection than a 20 weight oil at 200F. There is a lot of difference in viscosity between a 20 weight and a 50 weight oil at 200F. There is almost no difference in viscosity between a 5 weight and a 0 weight oil at 20F. What is the nominal clearance for the mains and rods in this engine? I couldn't find that number on the web. Is it 1 to 2 thousands?
GOD Bless and Thanks,
rich!

Is it possible its the time spent between ambient temperature and 200F where the damage is occurring?

[Fummins]

Attachment 22366

[Mechanic]

Dirt,
. . . . I know what you mean. I have blown up a few rotaries in my day. What turbo do you use?
GOD Bless and Thanks,
rich!

[Mechanic]

Atomic,
. . . . That is possible. Since these engines don't have an oil pressure or oil temperature sensor on them there is no way to tell without adding some gauges.
GOD Bless and Thanks,
rich!

[mohammad]

Atomic,
. . . . That is possible. Since these engines don't have an oil pressure or oil temperature sensor on them there is no way to tell without adding some gauges.
GOD Bless and Thanks,
rich!

I am 99% sure this engine has an oil pressure sensor. its wiring is right next to the oil filter. The light looks like a gravy boat. When you change the oil filter you can see the light stay on for a couple of seconds. I dont think it has an oil temperature sensor and im not sure why you would want one. Its not like coolant there is no way for the engine to modify its oil temperature if it wanted to. It has no heat exchanger.

[Mechanic]

mohammad,
. . . . That is an oil pressure switch. It is strictly binary. No pressure and the light is on and the engine is fried. An oil pressure sensor with an oil temperature reading can be very handy. By comparing the temperature and the pressure you can tell a lot about the condition of the oil and the bearings. On my RX-3 Turbo I ran both of them. I could tell when I was pushing the engine too hard. I always kept the oil temperature below 250F and insured that the pressure stayed above 40psi.
GOD Bless and Thanks,
rich!

I am 99% sure this engine has an oil pressure sensor. its wiring is right next to the oil filter. The light looks like a gravy boat. When you change the oil filter you can see the light stay on for a couple of seconds. I dont think it has an oil temperature sensor and im not sure why you would want one. Its not like coolant there is no way for the engine to modify its oil temperature if it wanted to. It has no heat exchanger.