Engine question

Hey guys I wanted to see if any of you might have some input on a little problem I have been having. I swapped in an engine from 96 into my '93 miata about a year ago because my old engine was having a lot of problems, such as really crappy oil pressure and it sounded like a diesel engine haha. So I swapped this one in with no problems until recently. The HLA's make hella noise, which I quieted with some lucas, but it still bothers me and on top of that my oil pressure is bad again....like I'm at 4 grand in 5th on the highway and the pressure is right at 30 lbs.... and when I'm at a light its like 20. I cant believe this is happening again and was wondering if anyof you have had any problems with oil pressure due to oil pump etc. I do all my own work on my car and have a lot of stuff done to it, but I really dont feel like replacing the oil pump if I dont have too. Any ideas would be greatly appreciated!

matt

Could be a stuck relief valve on the oil pump but your most likely culprit is a bad main bearing...

You'll probably want to have John Day look at it if you want it fixed.

RJ

You basing you oil pressure readings of the crappy OEM gauge or you using a real gauge??

The HLA noise is a NA Miata thing, on my old '92 It was my audiable indicator it needed an oil change. It had almost 150K on the motor when I sold it to ALL88.

It's true... the NA's make a helluva noise when the oil changes are due.

Hey ya didn't happen to use the oil pressure sensor of the 1.6 when ya plugged in the 1.8 did ya?? Have you replaced the sensor and checked the engine grounds??

What kind of oil pressure were you seeing after the engine swap? Did it go down gradually or suddenly? Do you think that the lifter noise started at the same time as oil pressure went south? That would make sense, and would indicate either a pump problem or bearing problem.

As for the HLA lifter noise, my 96 only got bad after about 2500 miles on an oil change. I found that using 5w30 oil or synth oil helped. If you really wanted to do away with the noise problem, swap in some solid lifters/shims and cams fron a 99-00.

Hey I peeked at my 93 Workshop manual an here is what it said on oil pressure:

Quote:

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INSPECTION
1. Remove the oil pressure gauge sender unit.

2. Screw the SST into the oil pressure gauge sender unit installation hole.

3. Warm up the engine to normal operating temperature.

4. Run the engine at 1,000 rpm and 3,000 rpm, and note the gauge reading.
For inspection of oil pressure
Oil pressure:
200-290 kPa (2.0-3.0 kgf/cm2, 29-42 psi)-1,000 rpm
300-390 kPa (3.0-4.0 kgf/cm2, 43-56 psi]-3,000 rpm

5. If the pressure is not as specified, check for the cause and repair. (Refer to Troubleshooting Guide.)

6. Remove the SST and install the oil pressure gauge sender unit.

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I'm not sure you are really having a problem. The OEM guages are weak at best. Also, it's getting warmer so your oil will be thinner thus more noise from your lifters. I was also talking to a mechanic about my lifter noise, and he told me to try using WIX oil filters, as they will flow better. I've switch on mine and went with thicker oil in the summer months, and my engine is a lot quieter, so far.

Thanks everyone for the feedback I really appreciate it. I have just been using 10w30 and throwing in the lucas oil stabilizer thats about as thick as maple syrup and that has def made them A LOT quieter. I was thinking about going with newer lifters and cams, so we'll see about that one in the near future. I did swap over the 1.6 sending unit since it is an mechanical gauge and the 1/8 just has an idiot light. I have noticed since it has been warmer the engine makes a bit more noise than before, but I was expecting that with the thinner oil because of the heat. Oh by the way who is John Day? I will def want to change out that main bearing if it is indeed the culprit. Thanks again for everyones help! I'll let you all know how it turns out.