55 replies to this topic

[RadioRon]

This is my first post on this forum, and it is about the first major engine repair I have ever done in my long life.  First some background.  I bought my Miata last season as my first race car, with the intention of learning how to race and also learning auto mechanics.  The driving part went OK for a while, but now I have jumped into the deep end on the mechanics part with a blown head gasket.  I have many questions and will post them all, as they come up, in this one thread, and am hoping for some help.  So, here goes....

 

First question:  why does the factory service manual caution against cleaning the camshaft pulleys and timing belt pulley with cleaning fluids?  I see this also in Grainger's Enthusiast Workshop Manual.  Is it because we don't want to risk having any fluids transfer to the timing belt?

Background:  There are two problems with my engine, the major one being that the head gasket is shot (broken open between cylinders 3 and 4), and the minor one being an oil leak in the front that has contaminated the timing belt and all the components around it with oil and grime. 

I expect to deal with the oil leak in the routine replacement of the camshaft seals and valve cover gasket, but I need to clean off the timing belt pulleys and can't see why it isn't ok to hit them with a water based cleaner followed by completely drying them.

 

For your amusement, I will put a photo up showing my gasket trouble.

 

 

 

Next question: what method do you recommend for keeping my oil passages clean while cleaning up the block?  Can I just stuff some rags in them?

[callumhay]

I don't know the reason the manual says what it does but I suspect it has to do with potential damage to the belt or the bearing mechanism in the idler and tensioner. If it's within budget, just clean the heck out of everything and then use a new belt and new tensioner and idler. If you are worried about residue then maybe use something that will completely evaporate like denatured alcohol.

If you are not taking the oil pan off, you are going to want to block passages with maybe some cotton wool. I'm guessing it's because you are cleaning the pistons while in the block. If your goal is to replace what's bad I guess I would not worry about getting the pistons super clean in case junk does find its way into the holes. If you are going to do a complete rebuild on the motor, it is not that hard if you have the factory manual and follow every step. The manual for the 1990-93 cars is more fool proof imo compared to the later manuals.

Even though Mazda parts cost more, my advise would be to use everything Mazda on the engine. If you are part of the Mazda racer program you get a nice discount. If not, you can still get pretty close with some of the Mazda dealers on e bay

Hope this helps
Cal

[dstevens]

While many think a blown head gasket can be a straight across swap many times there can be more damage than one can initially see.  Though that doesn't stop many, myself included, from cleaning it up and replacing the gasket.  If you've done just a mild overheating you could be OK but keep an eye out for other potential problems.  That's not a best practice but in many cases it's good enough.  

 

If you've blown a head gasket it's best to check if the deck and head are still flat.   Typically a head gasket blows when the engine gets too hot and the space between the deck head expands causing the gasket to blow out.  That can leave a slight warp in either of the parts.  You can do a rudimentary test with feeler gauges and precision straight edge.   

 

Give the valve train a visual inspection to see there are no bent valves, distorted springs, etc.

 

At the very least visually check your head for visible signs of the head cracking between combustion chambers.  Best case you'd have a shop use a dye penetrant (or you can buy some at Tooltopia and others) or have the head Magnafluxed. 

 

Run your fingers around the top of the cylinder to make sure the cylinder liner retaining ring isn't separated from the block and cylinder.  If it is you'll need to have the block serviced.  At that point don't put it back together, you've got a problem.  Any separation around the top of the hole is bad news.

 

You can use a rag to close the jackets and passages.  I use the 3M yellow auto body masking tape as it resists solvents and oil and leaves little to no tape residue.  Don't use regular masking tape.  

 

You can clean the timing belt by wiping with mild Simple Green.  What the FSM and books talk about are solvents and oils, things that contaminate rubber.  That said, with the front off you may want to consider replacing the belt while you are there.

 

Mazda does give you a good deal on parts.  Mazda itself does not manufacture things like bearings, belts, rings, etc.  For example the hydraulic lash adjusters (it's really a lifter...) are the same ones used by KIA and others at a much lower price.  Same with valve train components.  If you have a real parts person (not some chain) they can cross reference who exactly makes the Mazda parts and provide the identical part.  That said SM rules require parts from Mazda for the internals (or did last time I looked) but if you use the premium lines from places like Fel Pro, Mahle or Sealed Power you'll get quality parts.  If you use the lower end Engine Tech lines you may not get the quality of the Mazda OEM parts.

[RadioRon]

Thanks for the responses.   I can see how the manual is very cautious about having any mineral or petroleum solvents touch the timing belt, and perhaps it was written at a time when there wasn't much selection of water based degreasers, but I don't see the problem using a water based product on the camshaft pulleys.  The goal with such cleaners is to leave behind absolutely no residue of any sort, just squeaky clean metal, which can't be a bad thing.  I do see how you should avoid cleaning the tensioner and idler pulleys as I expect that they are internally lubricated with oil and we don't want to wash that away. 

 

I plan to install a brand new Mazda timing belt. 

 

I do not plan to clean off the piston tops, and my concern about contaminating the oil is only about the residue that I will clean off the top of the block, which I'm hoping to do with chemicals, not abrasives.  I am doing this work with the engine in the car, and only have two weeks to complete it before the next race, so getting the oil pan off is not in the plan.  I'm definitely overthinking everything and am paranoid, as you would expect from a beginner.  A mechanic (an SM expert) that I can talk to occasionally, thinks that I  should be fine with vacuuming/blowing any particles out of the cylinders with compressed air, followed by a wipedown of the cylinder walls along with an inspection to look for anything that may be scratching the walls.  I'm going to do that.  Then I'll put rags into the cylinders for the remainder of the cleaning.

 

I'm following the factory manual for the most part and cross referencing to a Grainger Miata manual.  The factory manual is pretty clear. 

 

My biggest concern is the fact that I don't really know for sure why the gasket let go.  This was the first race weekend on a known-good engine donated from a used street miata, that I just got installed in my car.  The only thing I did after the install was to replace the thermostat with a 160 deg new unit which I tested first.  There is a possibility that I didn't do a good enough job getting air out of the cooling system, but I think I burped it correctly.  The moment the gasket let go on the track I looked at my temperature gauge and it read just below 210 deg.  It was the hottest day of the year (which in my neighborhood means 90 deg air temperature), we were about 10 minutes into the race, I was pushing the car pretty hard and had spent about two laps drafting a Honda Civic pretty closely. 

 

Because of this concern, I'm looking at all aspects of my cooling system.   I've flushed out the radiator which is an FPS race rad, will be bypassing the heater core and will be using 100% water with a bottle of wetter added.  I will flush the cooling system as much as I can prior to closing it up for the next race, and am filling the system with the vacuum fill method (ie. Airlift).  The water pump seems to be fine as far as I can tell (turning easily, no slop or play).

 

I will not be re-using the head from my engine.  Instead I've got another head that I then had rebuilt at a good shop (machined flat, valves ground, new retainers, springs checked and replaced as needed, camshaft bores cleaned etc).  This should take car of the concerns about warpage or other head damage.  Haven't checked the block deck yet, but will give it a look with what straightedges I have on hand. 

 

I tried to put pieces of regular masking tape on the block's oil holes before starting cleaning, but the tape doesn't stick to the oily surface.  So I will try to use some cotton rags to close the holes. 

 

I'm interested in the Mazda racer program and will look into that.  Not sure if it applies to us Canucks but in any case I am already a believer in Mazda OEM parts.

 

I've got another question.  The factory manual (and many online experts) instructions call for the removal of the head plus intake manifold as a single unit, so that's what I did.  So, since I'm fitting a new head, I have to move parts over from the old head+manifold assembly to the new head.  Should I do all of that before installing the head back on the block, or should I put the head on the block first followed by the cams and the intake manifold?  Fitting everything to the head before installing it makes it pretty heavy and awkward to handle but I guess it removes the difficulty of how to get the intake manifold fasteners back in.  What do you think?

[dstevens]

You can clean oily surfaces with either brake cleaner or solvent based wax and grease remover (basically naphtha and toluene).  Either one will flash dry easily.   Either of those will take the oil and grit off.  Since you are racing and if you are like some (most?) of the rest of us bulk brake cleaner and an air charged dispenser (like a Sure Shot or the like http://www.sureshotsprayer.com/) is a good way to go.    As you've found regular masking tape isn't up to the task. You'd need something like 3M 301+ or better.  Rags and the heavy paper shop towels work as well.

 

I'm not a fan of thermostats in race cars.  You can search through the archives here and read other's thoughts.   When there is a system that needs some restriction (for example to prevent cavitation) I either make a restrictor or punch the center out of the thermostat.  It sounds like there is something up with the cooling system.   

 

To clean the parts prior to working on them I use a fuel system cleaner/additive called Seafoam.  Don't know if you have it up there.   Here is a before and after from my 1.6.  With the small brush in the pic there wasn't much effort required.  That's my "go-to" cleaner for engine internals.

 

[Steve Scheifler]

My first street car, purchased in 1975, was a 1969 Datsun 510 with a blown head gasket, which was the only reason I could afford it. So I know about being a bit nervous on your first DIY effort.

To get the old head gasket off I have never used anything but a razor blade. Many of those holes in the deck are coolant rather than oil but I don’t like bits of gasket in my radiator either so I take care cleaning it off. I run the blade under the gasket at angles away from the holes but ideally I also like to have a small vacuum running with the nozzle in my other hand guarding the holes. I do a final wipe down with brake clean on a cloth. A clean rag or something in the two down cylinders is fine, there is not a high risk there. Vaccum and wipe them out then lubricate lightly with engine oil. Personally I’d probably clean those piston tops a bit. I see that 4 is clean but 3 is not. Did you have coolant/steam come out the exhaust when it went? I would give some thought to why #1 seems especially dirty. Having injectors cleaned and checked is usually money well spent.

Installing the head with or without intake depends somewhat on your tools and patience. Probably easier with it on already if you have someone to help do it, but with the right extension and swivel socket the intake is simple enough to install after the head is on.

If you install the cams first be careful to have them positioned correctly relative to the pistons when you lower the head on, and likewise if you install the cams later, and don’t rotate them with any pistons fully up. After torquing the head I do recommend installing the cams first without the lifters or belt and spinning them to be sure they don’t bind. If the used head has ever been warped and cut there is a chance that they will and the average machine shop probably isn’t checking that.

[dstevens]

The #4 hole is clean because he got a free steam cleaning from the gasket failure.  

[Steve Scheifler]

That’s why I asked about the exhaust, but with such a big break in the gasket I sort of expected #3 to show a little cleaning as well.

[dstevens]

I've got a V6 from the race truck donor on the stand that's got one hole clean the five others mega dirty.  It took the head with it and likely the block.  With that big a blast I'd have thought the same that the hole next door would have gotten it too.

[RadioRon]

The #4 hole is clean because he got a free steam cleaning from the gasket failure.  

 

That's what I thought too when I first saw it, but there are no obvious holes in the gasket from coolant passage to cylinder.  But I guess the gasket could have leaked coolant in at those two holes between #3 and #4 and we might not see how.  Here's what the gasket looked like on the bottom side.

 

[RadioRon]

My first street car, purchased in 1975, was a 1969 Datsun 510 with a blown head gasket, which was the only reason I could afford it. So I know about being a bit nervous on your first DIY effort.

To get the old head gasket off I have never used anything but a razor blade. Many of those holes in the deck are coolant rather than oil but I don’t like bits of gasket in my radiator either so I take care cleaning it off. I run the blade under the gasket at angles away from the holes but ideally I also like to have a small vacuum running with the nozzle in my other hand guarding the holes. I do a final wipe down with brake clean on a cloth. A clean rag or something in the two down cylinders is fine, there is not a high risk there. Vaccum and wipe them out then lubricate lightly with engine oil. Personally I’d probably clean those piston tops a bit. I see that 4 is clean but 3 is not. Did you have coolant/steam come out the exhaust when it went? I would give some thought to why #1 seems especially dirty. Having injectors cleaned and checked is usually money well spent.

Installing the head with or without intake depends somewhat on your tools and patience. Probably easier with it on already if you have someone to help do it, but with the right extension and swivel socket the intake is simple enough to install after the head is on.

If you install the cams first be careful to have them positioned correctly relative to the pistons when you lower the head on, and likewise if you install the cams later, and don’t rotate them with any pistons fully up. After torquing the head I do recommend installing the cams first without the lifters or belt and spinning them to be sure they don’t bind. If the used head has ever been warped and cut there is a chance that they will and the average machine shop probably isn’t checking that.

I think I have enough socket stuff to put the intake on later.  I won't know unless I try.  I work without any help, so it might make sense to put the head on by itself first and put the intake on later. I like to follow the factory manual to keep me sane, and it puts the intake on later.

Thanks for the tips.  On that question about the appearance of the exhaust when it went out, I didn't think to look for white smoke, and nobody reported anything like that to me later, so I don't know.

[callumhay]

In terms of fitting the intake with the head before or after putting the head on the block . If you do not have help, or a crane it will be difficult to handle head and intake together. It is probably best to put both back in together as an assembly. It is doable however to put intake on after you have head on. The lower intake manifold bolts are all blind to see and you need to remember where they are. The one or two near the front are hard with you needing to get creative with the socket extension. Little hands and flexible hands will help! I have taped the nuts on to the socket to stop them from falling off, then started with hand rotation only until nut is well on. It comes down to what you think you can deal with to do the job right. It might seem easier to progressively build the parts back in the engine especially if this is your first time. For the guys who do this all the time I'm sure that leaving the intake on is a no brainier as they are used to the process/have help/ crane/experience.

The biggest pia will be getting the timing marks lined up. Take out the radiator if you have not done so already.you are also going to need some type of tool to hold the crank nose while you are fiddling with the cams. There are lots of videos out there, I found Mike, the Miata king( in Arizona I think) to be good. In watching him, he clearly had done it a lot.

[RadioRon]

I've decided that I have lower risk of screwing up the head gasket during installation if I just mount the head back to the block without the intake attached.  Sure, it will be harder to attach the intake, but I'll survive that just fine.

 

I hear you on the timing setup, but after studying the problem up, down and sideways, it doesn't seem too complicated so it won't be a huge deal.  I'll let you know what the reality is in a day or two.

[RadioRon]

Here's a minor update.  I was inspecting my old head assembly to see how hard it will be to install the intake manifold, and my eye strayed over to the front of the head and I spotted something interesting which could explain my oil leak.  First of all, both of the camshaft seals in the front are not correctly seated.  They are both pushing out unevenly.  The exhaust one is sticking out about 2 mm at the top, while the intake one is sticking out 3.4 mm (I measured it) from flush, mainly on the top as well.  That's a lot considering the entire seal is only 7 mm thick and the manual says they are supposed to be flush with the metal.  I'll take a photo later to show that. 

 

Second, the old valve cover gasket appears to be in good condition but it is surprisingly hard when compared to the brand new one I plan to install.  The difference is dramatic.  The old one is barely squeezable and reminds me of cheap imitation rubber.  The brand new one is soft, feels like rubber, and easily squeezes between my fingers.  Such a hard gasket could have had trouble sealing to that groove in the aluminum cover I think, as the inside of the groove is obviously not a polished surface.

 

So I think that I will be ok assuming new gaskets will fix this oil leak.

 

Oh, and yes, as everyone says, I can see that getting the intake manifold on will be tough.  I'm sticking with my plan though.

[RadioRon]

I learned another lesson today.  I was very concerned about bits of crap getting into my oil and coolant passages while I am cleaning the top of the block off.  But after some study, I'm not so concerned, and here's why. 

 

The most serious problem that I thought existed was that the bits of stuff would go down one of the 5 oil passages and eventually find their way into one of the critical bearing/ring/lifter passages causing critical blockage or other damage.  However, the oil distribution system won't let that happen (well, not easily anyway).  Only one of the five oil passages is critical.  That one critical passage has a little metal orifice called the Oil Control Plug  which is exposed at the top of the block but which has a relatively tiny hole.  This is the only oil passage that has critical post-filter oil meant to lubricate the valve lifters.  Oil passes through this plug, up into the head, under pressure.  All the other oil passages are gravity fed downwards and are essentially just draining the head.  So, it is necessary to prevent crud from going into that one orifice, for sure, but crud that goes into the other passages will end up in the sump where they should settle out to the bottom.  If they get sucked up into the oil pump, they, hopefully, will be caught by the oil filter causing no further problems. 

 

After reassembly of the engine, the common sense procedure is also to flush the oil system by dumping the first fill of oil after a short run time and refilling with fresh stuff.  That will help get crud out of the sump.  Oh, and change the oil filter too.

 

The coolant system isn't quite the same thing.  Coolant is passing upwards into the head through many passages between block and head.  So, if I get crud into those passages, which are relatively large, they will flow through the relatively large chambers inside the head and then out through either the radiator hose or the heater hose.  Since most engine coolant passages are relatively large, the main risk that this crud presents is that it might contribute to clogging up the radiator.  Happily, the radiator has significant redundancy of passages, plus the common sense procedure after the engine is re-asssembled is to do a thorough coolant system flush.  That should take care of gasket crud, dirt, bits of cleaning cloth, and other lightweight small particles.

 

Having stressed out about this for several days, its kind of a relief to understand how things work.

[dstevens]

You're still going to want to take care not to knock anything down in any of the jackets but plenty of people do in frame head gasket replacements and it turns out fine.  To clean the cooling system you can use straight water.  You can use whatever inexpensive dinosaur oil for the oil flush though I use something like Delo diesel oil for the first run then change to whatever oil I'd normally use for the second run.  Point being you don't need to do the cleaning cycle with an expensive synthetic or racing oil though I do use a new, good quality filter like a NAPA Gold or Wix brand (same parts, different packaging)  Another good practice for a race engine is to open the oil filter and check it out. I use one of these https://www.speedway...-Tool,2618.html but you can cut them open using aviation snips and a screwdriver as shown in the clip below.

 

 

[RadioRon]

I made a point of opening up the oil filter that was on the motor when the gasket failed.  I had a tough time getting that filter open (it was a Mazda filter), but when its guts were finally spread out for viewing there wasn't much in there other than a couple of metallic sparkles.  I also looked closely at what was on the bottom of my oil drain pan after pouring the oil out of it.  There were some interesting bits in there, a few tiny little hard pebbles (maybe 0.5mm across) and some visible metallic sparkles.  I showed them to my mechanic friend who declared them uninteresting and within the range of "normal".

 

Why do you use diesel oil for the first run.  Is it just because its cheap?

How can I hook up a garden hose for a thorough cooling flush?

[dstevens]

I've never done the garden hose flush.  I run it for 5-10 mins. empty, run again, etc.

 

I'd starting using the Delo because it was cheap and has a bunch of detergent in it.  When I'm that far along I'm usually into the engine more than replacing the head gaskets and likely to have some assembly lube to wash out.  On the race cars I made it a point to pull them and give everything at least a look.  You'll find some back and forth on using Delo and the like for flush/break in though I haven't had any issues.  The main point is you don't need expensive oil to do the flush.

[RadioRon]

Well, cleaning the block deck off is a bzzch of a job.  Here are some photos of where I am so far.  Seems good enough and it feels glass smooth to the touch.  Passes my fingernail test.  Do you think this is clean enough?

(PS: I saw the fuzzy remnants of cloth and vacuumed it all clean after I took these photos)

 

 

 

 

 

[dstevens]

That's plenty clean.  What did you use to clean it?