I’ve mentioned “the Miata project” on the podcast, giving updates each day, and I’ve promised to post photos, but I’ve been negligent in doing so. Honestly, when I get into working on the car I don’t think about photographing the progress often, and when I do it’s to send photos to a friend who also owns a Miata and is interested in what I’m working on.
But today I have some photos to share. It turns out that I took a lot more photos than I thought!
Here we go! That yellow lump is the Daytona Yellow cam cover, which will change color. See my home-made work light? That’s an old fluorescent shop light refitted with an LED ballast and bulb, hanging from two antenna mast sections supported by two speaker stands (a thrift store find). Eeeewwww! It’s time for a cooling system cleanup.The cam cover and belt covers are off, as are the thermostat neck, cam belt, alternator and power steering belts and pulleys.Intake manifold, exhaust manifold heat shield, and water pump removed.Getting ready to pull the cylinder head. No, that isn’t an engine hoist. It’s patient lift I found for $30 at a thrift store. It doesn’t reach far enough, but I got it to work. I later modified it and extended it’s reach.The head is now off the block and on the work table, and it’s obvious that some cleaning is in order here.Behold the focus of the project: the cylinder head. More specifically the valve stem seals, which are under those springs below the cams.This handy tool from Flyin’ Miata made compressing those springs simpler, but was a total failure on the other end of the process. I ended up using my old valve tool and a hammer to reinstall the spring keepers.How to keep your cylinder head still while working on it: Bolt it to the table.This little guy is the reason for the project. This is a valve stem seal, and one or more of them have been leaking oil into the combustion chambers. Odd find: there were two seals on one of the intake valves on cylinder #4.Crusty valves. And these aren’t the worst ones.The underside of the cylinder head. You can see how wet and crusty #4 is. That’s probably where the oil leak was.After a little cleaning. OK, a lot of cleaning. Each valve was cleaned by attaching a circular wire brush to a drill press and slowly working each valve until all the crust was eliminated.An overhead view of the engine block, pre-cleaning. The moisture is WD-40, which I sprayed into the cylinders to keep away rust while exposed.Ruh-roh, Raggy! I damaged the crankshaft timing gear trying to remove it. Had to order a new one – $52! See that stuff on the metal behind the gear? Looks like someone else did some damage in the past…Got the gear off. I had to use a propane torch to heat it up and expand the metal before I could pry it off of the crankshaft.This is the front main seal. It’s job is to keep the oil inside the engine. You can see more of that “stuff” on it. I learned that stuff is silicone sealant, and it’s there because someone broke part of the oil pump lip around the seal. I had to seal it again the same way, and hope it doesn’t leak again.Wrinkle-painting the cam cover. This is after a few hours of drying. It takes 24 hours for the paint to set up properly.Reassembling the head on the table. The wrinkle-painted intake manifold is reattached and temp sensors replaced. The blue paper towels are to keep debris and loose screws, etc., from falling into the bottom of cylinder head.Another useful tool from Flyin’ Miata. This is for removing/installing the crankshaft bolt. It attaches to this keyed plate and wedges against the water pump to keep the crank shaft from turning while loosening/tightening the crankshaft bolt – this is better than using the parking brake and putting the transmission in 5th gear, because it eliminates the possibility of the drive shaft twisting/flexing and gives you a true torque measurement.Here it is in use.While working on the car I replaced one of the power steering rack boots which was deteriorated, and that led to discovering that ALL of the ball joints were also deteriorated. My guess is that they were all original equipment – 30 years old. This photo is tools in a pile after finishing one replacement. That hefty silver c-clamp is the ball joint press, and it is just as heavy as it looks. It also likes to fall on any body part underneath it.Another cool tool: the Roloc disc. It’s a rubber bristled disk which has abrasive material embedded into the rubber. It’s the perfect tool for cleaning gasket residue off of head and block surfaces, plus most other metal engine parts. I also used it to clean the exhaust manifold heat shield and give it a swirly finish.This became a familiar sight. Almost every day parts were delivered, and I found more parts needing replacement. Yes, I do need to mow my grass.Reassembly begins!Getting closer! Here you can see the finished cam cover, wrinkle-painted black with aluminum painted recessed letters. Here’s a cool tip for painting recessed letters: Use a syringe to “inject” the paint into the letters and let it spread. (Amazon has “blunt” syringes for refilling inkjet printer ink cartridges) You can also see the exhaust manifold heat shield, which I cleaned with the Roloc disc and coated with satin clear flameproof paint.Almost there! Here you can see the new cold air intake setup on the right. The chrome bits are all some kind of heat resistant plastic. The heat shield (also cleaned with the Roloc disc and coated in satin clear flameproof paint) is sheet aluminum bent on a small sheet metal brake, and the supporting bracket is bent from aluminum strap. Previously the air cleaner was almost on top of the exhaust manifold heat shield, sucking in hot air.What’s a project without the odd leftover “mystery part”? You can see this part in one of the earlier photos of the head on the work table. I think it came off the intake manifold, but I can’t find where or what was mounted on it. I suspect it was a wiring harness mount, but the harness connectors are all old and brittle and their connection points have broken, so this bracket serves no purpose now.And here’s the finished project!
After replacing the radiator and refilling the cooling system I made sure the cam position sensor was unplugged and cranked the engine over until oil pressure began to build, then reconnected the sensor and turned the key. After a few seconds of rough idle it settled down and ran smoothly.
The engine temperature gauge, which had been intermittently working before, now works perfectly – I discovered during the project that the sensor wire was broken inside the connector, and also found another spot where the insulation had become brittle and broken. I repaired both problems and that took care of the finicky temperature reading.
But… it still smokes. In fact, if anything, it’s worse than before.
That means the cause of the oil seeping into the combustion chamber(s) wasn’t faulty valve stem seals. It’s something else. It may be a really worn valve guide, but that’s what the seals are supposed to do – seal out oil. From examining the photos I can tell that the rearmost intake and exhaust valves in #4 had a lot of carbon buildup, so I suspect the oil is running down one or both of those valve guides
It also has a new valve tick. It isn’t loud, but it’s there. I traced the sound to the #4 cylinder. One of the lifters may be sticking.
I took a drive to heat the engine up and see if that helped the lifter settle in, and it helped a little. On the drive it ran poorly at low RPM, stumbling and hesitating.
When I got back home I pulled the spark plugs and checked for signs of oil. Plug #4 has black smudge but all the rest are clean. I suspect a lot of oil is getting into #4, and that’s causing it to misfire.
At this point, honestly, I’m at a loss. I’m not an auto mechanic. I’ve just learned how to work on this little car as a hobby, and now I’m beyond my level of expertise. It looks like my options are: 1. Have the head rebuilt. 2. Buy a rebuilt head.
We’ll see what happens next.
UPDATE:
After some thinking and tinkering, “Lil Smoky” is no longer smoking, and running better than it has in a long time.
At breakfast Saturday morning I described how the car was smoking to my friend Mike. He’s been working on cars most of his life, and it was because of his encouragement that I started getting deeper into working on my little car instead of taking it to a repair shop. His puzzled expression told me that the way it was smoking didn’t make sense to him – it wasn’t smoking while idling, but was on acceleration. That made me think that maybe oil wasn’t getting into the cylinders through the valve guides, but from below. Maybe there was too much oil in the engine.
So I checked the oil level and it was high. I had put too much oil in. (Stupid me!)
Sunday morning I drained some of the oil, checked the level and it was on the “Full” mark on the dipstick. I took the car out for a short drive, and it smoked like crazy at first but stopped smoking soon afterward.
The excess oil was the problem.
But it still stumbled badly upon acceleration, so there was more work to do. I suspected that the timing was off, so that was my next thing to check. My thrift store timing light score from a few weeks ago turned out to be a dud, so I picked up a cheap one at Harbor Freight Tools (which is going back because it’s a piece of junk) and started tweaking the timing. Since this is a 30 year old car the timing marks on the harmonic balancer are hard to see, plus there are several scratches which can be mistaken for timing marks, but I eventually found the right one and set the timing according to recommendations found online.
After adjusting the timing I made a 40+ mile round trip and the little car runs great! The stumbling is all but completely gone (what’s left I think is a fuel injector problem) and acceleration is much snappier than before.
Since I fiddled with the steering components I’ll need to get the alignment checked, but other than that I think the Miata Project is a success!
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