///tonic

iTrader: (1)

And the progress marches gradually on...

I pulled the camshafts today and discovered 3 stuck lifters (all the other lifters have some squish to them before you press hard enough to compress the valve spring). The lifters are stuck on:
Cylinder 3 Intake valve
Cylinder 3 Exhaust valve
Cylinder 2 Exhaust valve

could two stuck lifters on the same cylinder be sufficient explanation for my symptoms?

Since the head is off at this point, I plan to take it in to a shop for inspection and valve cleaning/lapping at the least.

Maybe a DIY port/polish.

sn95

iTrader: (2)

The stuck lifters are also known as "collapsed" lifters. Typically a collapsed hydraulic lifter will cause valve train clatter and loss of power (valve won't completely open with a collapsed or stuck lifter thus causing cylinder to lose power); it should not prevent the valve from completely closing (which causes burned valve faces and seats).

The collapsed lifters on one cylinder would cause lower readings of that cylinder on your static cranking compression test; they would not cause the cylinder leak down test numbers to be lower.

BTW, 80psi is the standard leak down test pressure for aircraft engines. Any cylinder in the 70s is considered good, cylinders in the 60s are considered marginal but still airworthy (by both Continental and Lycoming) while anything below 60psi is grounds for additional diagnosis and repair.

sn95

iTrader: (2)

Given that you have found 3 collapsed lifters so far, it is probably safe to assume that your motor has suffered from mistreatment in the past (probably lack of frequent oil changes and a lot of stops on the rev limiter).

When you have the head inspected (hopefully by a shop that deals more with Asian DOHC 4 bangers than OHV SBC V8s) make sure that all the valves are checked for bent stems, the valve guide clearance is within factory limits, and the valve springs are checked for static height, installed height and trueness as well as open and closed seat pressure.

You may think about cleaning and/or replacing all of your HLAs; you have already had a 20% failure rate....the other 13 may be on borrowed time. It is a lot easier to do this with the head off the car and apart than to wait for another old HLA to fail after you put everything back together. You can get new HLAs from KIA for a fraction of what Mazda charges (search Miata.net or this site for more info). You can disassemble and clean your old HLAs that are not stuck. I'm not sure if you will be able to take apart the 3 that are stuck (may have to soak them in solvent for a few days). If you get them apart you should probably try to source new internal springs and replace them.

FWIW, used HLAs should go back into the same lifter bore they were removed from.

///tonic

iTrader: (1)

Perhaps I should clarify. These lifters are not stuck in the collapsed (or closed, or fully compressed, however you call it) state. They are stuck fully extended (open, uncompressed, whatever).

Correct me if I'm wrong, but I believe that as a result the associated valve cannot fully close.

I'm looking to follow this tutorial in hopes of restoring my lifters. Or, failing that, I'll just replace them.

Sure enough, I just went down, labeled each lifter (in case I clean and re-assemble instead of replacing), and removed them from the head. Then I pulled apart one of the 'good' lifters and one of the bad ones. The good one came apart easily, and had a bit of reasonably clean oil inside. The bad one took much more force to pull apart and was full of black grossness (bad one on left, light reflecting off black sludge makes coppery color):


I also re-performed the flashlight check now that the cams are off. All the valves seal sufficiently to block out light now.

sn95

iTrader: (2)

Ouch! If you had 3 HLAs stuck open, you may have 3 burned valves! A lifter that prevents a valve from fully closing causes a loss of compression & power and can also cause burned valve faces (typically the exhaust burns before the intake). At a minimum, I'd would carefully check the 3 valves and seats that had the stuck open lifters.

I see you've found the good HLA cleaning write-up on Miata.net; that is one of my "someday" projects.

Stein

iTrader: (46)

If you check ebay, there is a vendor that sells a full set of HLA's for $80something. For that kind of money, I would just replace the set when rebuilding the head. You are already going to drop $20-30 on the three as individuals.

bryanlow

iTrader: (10)

I've got some spare HLAs out of a '95 if you want them. Head was damage but most of the lifters were ok. You'll need to pay for shipping tho.

///tonic

iTrader: (1)

Update from the machine shop: one intake valve of cylinder #3 had an aluminum shaving stuck to the seat, preventing closure.

Major F.

Because it's entirely my fault: I drilled and tapped the IAT sensor hole with the manifold on the car. I attempted to blow any shavings out by reversing the flow on my shop vac and blowing into the hole, but that was not sufficient, obviously, to clear everything out. Damn expensive mistake, but I'm going to chalk it up as an educational experience.

He also found that the intake and exhaust valve springs were interchanged at random... and was generally not impressed by the head work formerly performed. And I've brought the head home this weekend for some DIY porting. Combine those two things with some new/rebuilt lifters, and I think I'll be much better off for the rebuild anyway.


One quick question:
Can the intake valves be ground a second time (this head has already had one valve job)? The shop showed me the valves after grinding, and there's not a whole lot of casting meat left anymore: there's just about .020" from the ground valve seat surface to the edge of the combustion chamber surface.

sn95

iTrader: (2)

Sorry to hear about the aluminum shaving getting stuck on the valve seat (I'm in the process on trying to do an on-car sparkplug insert repair on a SOHC modular Ford so AL shavings getting stuck on valve seats is not good news!).

Are you asking about "margin thickness" (edge of valve between seating face & top of valve head) or valve seat contact width????

My 1.6L FSM shows the Margin spec as 1.0mm (.039) for both intake & exhaust valve and the seat contact width as .8-1.4mm (.031-.055). There isn't really a "margin" spec for valve seat width; the valve just needs to be seated properly (seating height can be adjusted up/down by making off angle cuts).

If your valve seats currently only have a single face, ask your machinist about doing a 3 angle valve job on the stock seats. This increases low lift flow and will help your DIY porting job (as long as you make sure you don't ding the seats while porting! Worst case, if you have one or two bad seats, the Miata AL head has pressed in seats which can be replaced relatively easily. Just make sure your shop is used to dealing with DOHC AL heads....it is always painful and expensive to "pay" a shop while they "learn" how to work on a motor that is new to them.

///tonic

iTrader: (1)

Thanks sn95. Looks like new intake valves are in my future: I was indeed talking about the 'margin thickness'. Funny, I didn't even think to check my shop manual for a spec for that. I'll have to flip through that section.

The shop I took it to does a lot of V8 work by the looks of it, but he was recommended to my by my BMW mechanic (a Turner Motorsport race tech) as the only local shop to go to. And he says he's done quite a few of the Miata heads.

He was pretty surprised about the aluminum shaving: apparently he's done hundreds of spark plug Helicoils and never had an issue.

sn95

iTrader: (2)

I'm hoping to have the same "luck" on my spark plug insert. What's the basis for your Turner tech's referral??? Turner Motorsport is an ICON in BMW circles (alas, my E36 M3 is now in servitude to a shrill woman who can't drive it...Divorce is Painful but worth it!) but why is your TMS rep referring you to this shop? Does this shop do the head work on TMS DOHC BMW motors????

Mitch

///tonic

iTrader: (1)

Ha, not exactly. If I wanted a race head, Marc would have sent me somewhere else (ship the head out), presumably based on his Turner experience. He still works for Turner on race weekends, but he's opened up his own shop now, and for regular street cars, he sends all machine shop work to this guy - a one man shop with a lot of years of experience. He's extremely fastidious, and Marc said he's never had any issues with his work.

sn95

iTrader: (2)

Sounds good, just make sure to ask about a 3 angle valve job on your head!

8387supra

DON'T reuse the ARP studs. Think of getting it all together and it not sealing.
Take the block to a machine shop, and get new studs and a gasket along with a new head.
Why cheap out and reuse head studs?!

sn95

iTrader: (2)

You're joking right??? Do you really think 15lbs of boost is going to stretch ARP studs??? NMRA racers running 35lbs of boost get a full season out of ARP studs.

///tonic

iTrader: (1)

Okay, just assembled an order with FM. I feel like I'd be stupid not to replace all the gaskets and seals while I'm in there. And I need the new intake valves. That all brings me up to ~$500, which is a bit hard to swallow.

I know I could get it cheaper, but I also know I'm getting quality parts and service from FM (most of the cost is in the 100 dollar metal headgasket and the 180 dollar stainless valves). Any second opinions on vendors or on choice of parts?

Arkmage

iTrader: (3)

Just so we clear this up for all the newbies now...

1) Replacing the head is almost never necessary, facing it might be.

2) You do not need to take **** to a machine shop to have studs removed and/or a head gasket installed.

3) ARP studs can be used nearly infinite amount of times on a miata as long as they are not over-torqued.

4) This guy was banned for a reason. He's ******* retarded.

sn95

iTrader: (2)

My suggestion would be to make sure you replace the OEM umbrella style valve seals with Viton seals. Vendors (either on this site or Miata.net) sell new Viton seals for less than Miata sells the stock umbrella seals.

Headgasket: What makes you think you "need" a $100 metal head gasket vs. an OEM gasket??? I think you'll find that head gasket seal is more than adequate with the OEM style gasket, ARP studs and a METICULOUS cleaning of both the block deck and head surface. Make sure the machine shop working on your head checks the head for "trueness".

ARP's website should also have very specific instructions regarding now to install the studs (including appropriate cleaning and lubrication) and how to properly torque the nuts on the head (in torque steps using the Mazda tightening sequence).

Intake Valves:
Why aren't you replacing any the exhaust valves?? Is the "margin" adequate on all the exhausts and below spec on all the intakes? That notwithstanding, there aren't that many companies making quality after market SS valves (Manley, Ferrara, SI to name a few) and FM is buying their valves from one of them.
See if FM will tell you the manufacturer and special features (backcut, turned-down stem, etc.) of their valves. Price valves with some of the other suppliers on this website and Miata.net and see what you come up with compared to FM.

Arkmage

iTrader: (3)

The viton seals seem to go for about $1/ea + shipping. I'll send you the 16 I've got in the garage for $15 shipped (provided you are in the states). PM me if you are interested.

///tonic

iTrader: (1)

Please Help!

I got my head back from the machine shop 9 days ago and I still can't f-ing get the Miata running.

I ended up ordering all my parts from flatlander racing. These included:
- Ajusa Full Gasket Set 50128100
- Supertech Intake Valves MAIVN-1100/2
- Supertech 58 lb single Valve Spring Kit w/ Ti retainers SPRK-MM16S-KIT

A word of warning, the supertech spring kit requires 99+ valve keepers (like the FM kit), which I only found out from the packaging after the kit was delivered. I ordered those from finishlineperformance.com

While I was waiting for parts, I rebuilt my lifters per this guide, and did a DIY port/polish per this guide.

So I got the head reassembled last Sunday, and everything back on the car and buttoned up on Monday (including new front main seal). Super psyched, I hop in and crank the car over, and get ... just a slightly slow turnover, no real sounds of combustion. Being 3:00am at that point I went to bed.

Since then, I've dropped a couple fresh gallons of 93 octane in the tank, charged up the battery, and quadruple-checked all the vacuum lines, the fuel lines, and the timing belt alignment.

The plugs are all making spark, and they're damp with fuel after cranking. I did re-check the ignition coil resistances, just to be sure. The car does seem like it's cranking over a bit slow. The AFM flaps open and shut as you crank, and I can hear the exhaust sort of burbling/popping as I crank. But that's it. The boost gauge reads no vacuum when you crank. The oil pressure sits ~35 during crank.

Just for fun, I tried a cold compression test and get virtually nothing on all cylinders, maybe 5 psi. Not sure if that's significant or if that's normal on a cold motor.

I'm totally lost at this point. Everything I can think of to check checks out correctly. Can anyone please give me some insight, troubleshooting ideas, or anything? Is there anyone in the Boston area that would be willing to come take a look?

Frustration extremely high.