38 replies to this topic

[Justin Fowler]

I just bought a 99 donor and have no history on the services done to this car. The car claimed to be blown from over heating, but I had rebuilt what they tore down and it started right up. The car runs good, the temperature never goes over half way on the gauge and I replaced the thermostat just to be safe. The cooling fans kick on, water pumps through the radiator, so I think the over heating problem is solved. (I hope)

Car has 200k miles

Bad thing, the engine has a slight tick, I have read up alot about it and it sounds like HLA's to me but I am not 100% sure. When I drained the oil it had a slight silver coloration, oil did not look like it had water but I will cut the filter tomorrow to make sure there are no big chunks of bearings. I used Valvoline 20w-50 that was given to me just to try out, probably need lighter oil but the tick is still there.

What suggestions do you all have to service this engine. Not sure what all I should throw at it right off the bat but I was hoping I could get good use out of this engine.

[Jim Boemler]

"Blown" from overheating can be as simple as a head gasket, or it can be terminal. Sounds like you may dodge the bullet. At 200k, the bearings could well be self-destructing, though, indicated (maybe) by the silver color. If you're trying to salvage some useful time on this engine, get an analysis on the oil. Be sure to tell them how many miles are on it (presumably very few). They can tell you a lot about the engine's condition from that.

The downside, however, is that if the bearings decide to part company, it will probably be catastrophic. Rather than having a rebuildable core, you could end up with a pile of scrap. Not the end of the world, and perhaps even the right course, but go in with your eyes open.

BTW, evaluating noises by recordings is very spotty. That said, to my ear that doesn't sound like HLA noise, and I wouldn't call it "minor". I hear more air in the noise, and more resonance. What comes to mind is a burnt intake valve (or several), but don't go taking that to the bank. What did you rebuild?

[Justin Fowler]

I figure a blown head gasket would lead to water in the oil, depending how long it has been blown. The oil seemed to be fairly new, not to burnt but not brand new. Simple things make me believe the car was "taken care of" like new inspection, registration, new air filter, pretty new oil/filter, tires in fairly good shape.

My biggest fear is a bearing giving out, I have dealt with it a few times in my dirt track career and it is never a good feeling.

I wish I had a better recording but there is alot of air noise when I rev it. All I have done to this engine is completely clean the throttle body, reinstalled TB and air intake, put the valve cover back on, plugs and wires, and figured some wiring they had disconnected.

[Keith Novak]

It does sound a lot noisier than normal lifter clatter. Hard to tell much just from the audio on that video. Did you perform a leakdown test? What was checked, measured, etc when it was "rebuilt what they tore down"? I had a used motor that sounded fine, didn't overheat, but leaked like hell from the valves and when I tore it apart I dumped oil out of the intake manifold.

[Justin Fowler]

I have done no tests yet, to late in the night to do compression/leakdown test and I plan on doing that tomorrow. But there is a slight knock when the trans is in neutral, when you push in on the clutch it goes away so i think it is just low on fluid considering it makes no noise on until the fluid heats up.

[Keith Novak]

A head gasket won't necessarily lead to water in the oil. You can get a "block test kit" from Napa for about $20. It will test for combustion gas in the cooling system. Takes about 15 minutes to get temp and then 1 min to see for sure. When I blew a head gasket on my Dakota, no smoke, no water in the oil, tires were primo, oil filter was fresh, performance air filter, but combustion gasses in the cooling system none the less.

[Jim Boemler]

I figure a blown head gasket would lead to water in the oil, depending how long it has been blown.

All I have done to this engine is completely clean the throttle body, reinstalled TB and air intake, put the valve cover back on, plugs and wires, and figured some wiring they had disconnected.

Ah, so you haven't been inside the engine at all. I had assumed by "rebuilt" you had at least taken the head off. So now, do a leakdown. What you'll probably find is very large values in two adjacent cylinders (either 1/2 or 3/4). You'll also see air escaping from the valves of the cylinder you're NOT pressurizing. What's probably happened is you've blown the head gasket, between two cylinders, and air is getting pumped back and forth between them. The leak probably doesn't include either oil or water passages.

[Justin Fowler]

Good possibility Jim, I don't do much engine work myself unless it is a sbc 350 lol

I will have to get this checked out tomorrow, my father thinks it is nothing to worry about but I DO NOT want to take any risks. I guess my first step will be the leakdown and a compression test tomorrow.

[Jim Boemler]

Data is good. Good luck!

[Justin Fowler]

Thanks Jim, one more question. How often do you replace timing belt and water pump? I know under normal maintenance you replace every 60k but what about under racing conditions? I am new to timing belts and fuel injections so this spec miata is a whole new beast to me compared to my dirt track car.

[Jim Boemler]

I personally have always had good luck with timing belts, and I don't replace them based on mileage. Always inspect when they're off, and replace if worn, teeth are getting broken, or especially if cut. If you're in a high smog area, you might want to beware that smog attacks rubber.

Also beware that somebody will soon pop up and tell you that you should replace every XXX regardless. Neither of us is completely wrong.

[Tom Hampton]

Also beware that somebody will soon pop up and tell you that you should replace every XXX regardless. Neither of us is completely wrong.

I don't replace my belts just because I accidentally watched an adult film.

[dstevens]

Good possibility Jim, I don't do much engine work myself unless it is a sbc 350 lol

I did too and it's not too different once you get your head around the injection, valve train and computer. It's a fair amount smaller and other things I found most different were the deep well plug wrench and needing a different valve spring tool and 12 pt for the head bolts.

Sure seems like a head gasket. Leak down will tell. I'm just buttoning up a rebuild of a 92 1.6 of new HLAs, cleaned cores, measured all of the valve train, cores and rotating assembly, seals and gaskets, rings and bearings. The cores speced well but some of the valve train parts are getting close to tolerance. If it's a 200k street engine I'd at least give it a measure before racing it. If by some chance you spin a bearing you'll go from having a good block and perhaps rod and crank cores to having a bunch of broken iron.

[Jim Boemler]

I don't replace my belts just because I accidentally watched an adult film.

Texans must be undersize. I have to.

[dmathias]

Is this going to be an SM? You're going to want to throw a pro motor at it, aren't you?

[davew]

Sounds like valve train noise to me. But a LLOOOTT of it. I would be very leary of racing this engine without a complete rebuild.

Head gaskets can blow 3 ways. Keep the comments to your selves!!!

1-externally, leaks oil or water out the side of the block. My old Mustang GT3 car used to do this.

2-Internally to a water jacket. This will usually cause a chocalate milk shake effect in the oil, but not always.

3-Internally between cylinders. Usually between the center cylinders as the head warps due to over heating.

Dave

[Tom Hampton]

Sounds like valve train noise to me. But a LLOOOTT of it. I would be very leary of racing this engine without a complete rebuild.

Head gaskets can blow 3 ways. Keep the comments to your selves!!!

1-externally, leaks oil or water out the side of the block. My old Mustang GT3 car used to do this.

2-Internally to a water jacket. This will usually cause a chocalate milk shake effect in the oil, but not always.

3-Internally between cylinders. Usually between the center cylinders as the head warps due to over heating.

Dave

::ROFLMAO::

I have lots of comments for XXX and externally and internally blown...I just can't bring myself to type any of them!!!!!!

I'm a little worried that dmathias may explode trying to contain himself.

[Jim Drago]

The car doesn't have hydraulic lifters, they are solid. The lash is probably way out, but the motor is likely wore the &*(^ out...

You can check valve lash and see what you get, that may get some of the noise out. But I would do a leak down and compression and likely start from scratch and rebuild or replace. At 200k, over heated.. it is an accident waiting to happen IMO. You are likely to take a good rebuild-able block, head and crank and ruin it when it explodes.
Jim

[Justin Fowler]

Alrighty then, when you do a compression test, what is a average compression rate? how much psi is a good cylinder on these miatas?

[dstevens]

Better to do a leak down as well. A compression test will tell you if a cylinder is weak compared to the others. A leak down will tell you where the problem originates. If you compression test first you can at least start on the worst of the bunch. On the old forum it seemed to be 170-185 psi on a 1.6. I don't have a 99.