A Problem Diary - New 5.0 NA from east TN
 

Hello v8miata! Just got two NAs, one has an 87 5.0 transplant. The miata is supposed to be the lighter, rear drive alternative my STI for cruising mountain roads. It's also something to do in my spare time.
However, i may have bit off more than i can chew i.e. windows & power steering don't work, needs bigger clutch master, exhaust re-routing incl x pipe etc etc etc.

Here's the v8
230k+ miles, odo doesn't work. Not sure of engine mileage.

https://www.v8miata.net/attachment.p...ine=1457713155

https://www.v8miata.net/attachment.p...ine=1457713155

And here's what used to be the daily driver. Waiting on new oil pan, hood, and a frame straightening.

https://www.v8miata.net/attachment.p...ine=1457713155

Hey welcome to the forum! Too bad you jumped on a few weeks too late most of us were just in your neighborhood. You sure do live in a great part of the world for car guys. So did you build the V8 car or buy it that way? Post up your issues and you'll get plenty of help around here.

Just missed you! I hope to attend Miatas at the Gap.
Here's some more info about the car from my miata.net thread.

Here's how the car came to me:
94 Miata
5.0 V8 from 87 Mustang, stock with new gaskets throughout
BBK headers & glass packs
New water pump
T-5 trans with new clutch
Short throw shifter
Aftermarket M3 aluminum radiator
Turbo 2 RX-7 limited slip rear end
Melling high volume oil pump
Autopower Spec Miata Roll Cage
Eibach Springs with KYB red adjustables
Flyin Miata front sway bar

Pics https://picasaweb.google.com/lilblub...sRgCKLH0aeRksz
Video from an autocross run

Friday on the way home from work I noticed the water temps getting high. Just pulled into the driveway and the radiator cap spewed a shower of rusty water. Turns out the freeze plugs had rusted through.

Attachment 6375

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Thanks to autozone and youtube i managed to replace them. It only took all saturday afternoon lol. Happy it wasn't worse.

Attachment 6377

While that freeze plug was out I would have pulled the radiator out and flushed it and the block. That rusted freeze plug is a major red flag that the engine has not lead an easy life. Who knows what contamination has occurred to the rest of the cooling system and heater core.




Bill S.

Next up is a new power steering pump. Also it smokes a bit and just took 1 qt of oil after 2 weeks of driving. Looks like the engine will be coming out eventually.

Thanks for the tip! There was quite a bit of crud built up behind the freeze plugs. One way to flush is remove the radiator drain plug and run a hose through it with the engine running. Are you suggesting a more thorough method?

Not certain who told you your method, frankly, I would not ever do it that way.

Pull radiator, take to shop and have it hot tanked.


Pull thermostat housing, upper and lower hoses and run water through engine with hose on full without engine running at the very least.


There are ways to run a flush under pressure with a special machine, but I prefer a simple at home method.

Bill S

It is just a matter of time until the rest of the freeze plugs begin to fail.

You have a little different situation than a normal flush with 2 freeze plugs out. So I would start by pulling the rest of them and flush every hole every which way you can. Just shove the garden hose in and blast away. Some of the plugs will be hard to get to (like the back of the heads) but for a freeze plug to rust out means that thing has been very poorly taken care of and the one you don't change will leave you on the side of the road sooner than later.

Once you get as the new plugs in you can use the normal method of flushing a system. The way I do it is disconnect the return heater hose from the core and put the garden hose on the water pump and fire it up. You can do the same thing with the lower radiator hose. Take it off the radiator and put the garden hose into the hose that feeds the water pump and run the engine. Then flush the radiator out in both directions.

Looks like a sweet car and I'm sorry you are finding these issues in it.

As luck would have it...
Before I had a chance to properly flush the engine and radiator it started misfiring badly. It wouldn't even idle. This was last Tuesday and Southern Worthersee was coming up. So I decided to park the miata and install a bigger oil pan, pick up, and baffle in the sti.

Back to the misfire. First i checked inside the distributor cap. There was silver looking buildup on the points so i cleaned that off. Then i made sure none of the spark plug wires were touching. What we know - it's smoking out the passenger side exhaust, these two cylinders aren't working (didn't try more because my cousin didn't like getting shocked) and cyl#1 is super lean.

Attachment 6352

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A 302 & a 302 H-O have different firing orders. Make sure you have the wires on correctly for your application. They will both run if wired wrong, but not so well.

Lateral could I trouble you to take a minute to update your signature with your name and what your car is so we know what you are referring to when you post. Edit your signature here (click)

Thanks!

Here's some more info -
It wouldn't run at first (few weeks ago)
Replaced the TPS and adjusted it & distributor until it would idle.
For a few weeks ran great, including a day at the Dragon (2 days before misfire started)

Now, the white spark plug's cylinder blew 130 psi (dry, cold engine). However, the injector for that cylinder doesn't seem to be pushed as far in as the rest. This cylinder is #1.

Thanks for the tip about firing order, I will check that asap.

So you are saying cylinder 2 and 6 are not firing? Those are the spark plug wires disconnected in the pictures. What did those spark plugs look like. OK? fouled?

As far as the injector being pushed in, are you referring to the electrical connector on the injector or the injector itself? The injector fuel wise is sealed to the intake and injector rail via O rings on the top and bottom so you can actually rotate them if you want and may have some up and down motion as well. Not a problem unless you have fuel leaking by the O rings.

You had me worried with the "points" comment! Must be the tips of the dist cap inside for each plug post!

Mike

Spark Plug pics

Cyl 2
Attachment 6342

Cyl 3
Attachment 6343

Cyl 4
Attachment 6344

Cyl 5
Attachment 6345
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Cyl 6
Attachment 6347

Cyl 7
Attachment 6348

Cyl 8
Attachment 6349

Here are all the plugs and compression numbers. Dry, no oil added. Cold engine.

Attachment 6341

A few weeks ago (before we got it running) cyl 5 spark plug was perfect. I damaged it (noob) and bought a new one but O'reillys sold me an Autolite 2545 or something with a 0.60 gap!! It is by far the worst looking. Just now realized :(

Did my buddy get the tps and distributor settings wrong?

Also, not sure why cyl 7 is abnormally high. The first time it blew 175 psi.

I had to drive it for a few days with the misfires. This might have put the working cylinders under higher load.

I suppose this all means new spark plugs (motorcraft), Ford racing wires, and get the timing set professionally.

Yes we have major spark plug issues lol.

Here is injector #1 at an angle but thankfully there is no fuel around it... looks like the rail is bent

Attachment 6337

Looking over the engine I found a broken vacuum hose clamp. Even worse, it was attached to the coolant hose part of the throttle body spacer. Definitely a vacuum leak. The oil is coming from my crankcase vent on the oil filler tube :(

I attached the hose to its proper port and capped the coolant line.

Attachment 6336

New Motorcraft spark plugs didn't fix the misfire. Neither did fixing the vacuum leak. I started it up and it still sounds like an old John Deere tractor.... pop pop pop pop. Maybe 2 cylinders firing lol. Got some Ford racing plug wires on the way!

So did the freeze plug fixed the blowing out the rad cap?

I have the same issue (blowing rad fluid out of cap) and I'm hoping it is not a head gasket.

Any speculation as to why? Leak = pressure loss...?

I wish I could help but don't know much about cooling systems. All that comes to mind is that the water got too hot, boiled, and steamed creating high pressure. Yes, the freeze plugs kept coolant from leaking and getting too hot. No issues since.

As long as you have the correct antifreeze mixture (raises boiling point) and coolant level I don't know why your cap is blowing. Unless it's bad? I think different caps have different pressure ratings but I'm kind of guessing at this point. Is your radiator big enough? Also might be the thermostat is sticking closed... A blown head gasket would show up on a compression test. Compression gauges are not that expensive if you don't have one. Best of luck! I'm interested to know what you find out.

Misfire Troubleshooting
 

Installed new Motorcraft spark plugs, still misfires
New Ford Racing spark plug wires, still misfires

However, it would idle... at 500 rpm lol. By touching the header tubes I determined that only cylinders firing were 1, 5, and 8. Yep that's right it is effectively a V3!
Pulling the plugs showed they were getting gas.
Using a screwdriver we checked for spark and got plenty of arc.
So fuel is good, spark is good, compression is good, that leaves air.

We sprayed maf cleaner around the intake manifold and the engine picked up noticeably. Next we removed the upper intake manifold. Almost all bolts on the lower intake manifold were loose!!!

After tightening the bolts and putting humpty dumpty back together we still had misfire :( BUT it was idling at 700 rpm! So not a total loss. Spraying maf cleaner indicated we still had a vacuum leak somewhere.

The conclusion is 1. that the lower intake gasket is shot or 2. the lower manifold warped when it overheated a few times.

Attachment 6310

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Yes we cleaned this after! Apparently it hasn't see daylight since 1987.

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Upper intake manifold gasket is good. Here is my buddy tightening the lower manifold bolts.

Attachment 6313

The mechanic that looked at it this afternoon suspected head gaskets. He said do a compression check with all spark plugs out.

The shop was about 5 miles down the road. Driving there I wasn't able to go over 30 mph on a long hill. Vacuum check was good so the lower manifold gasket isn't the problem. Something is wrong with the wiring because their scanner wouldn't connect to the ECU. During the testing they revved it up hard alot... and when I left it felt like it was down to 2 cylinders. The long hill now required 1st gear and barely moving. Finally it wouldn't go any further and my buddy towed me home! This sounds like the gasket is giving out.

I really want to take the top end apart and see what's there. So that is the next step.

It leaves air and timing. Good spark has to happen at the right time and fuel too. It's pretty concerning that the shop could not read the electrical and that could be the problem. I'm not very knowledgeable on Fords these days to address the electrical but the guys here can chime on on that.

However I like the idea of the compression check a lot. That will tell you much about what is going on in the motor and given the heating issues I think a very good place to start.

I wonder if it would be worth the effort to pop the front cover off too and see if the timing chain has jumped.