13 replies to this topic

[Dan S]

After getting a rock in the koyo radiator in the Miata the last weekend I was out I decided to add a coolant pressure sensor to my AIM mychron 3 XG. The temp sensor never went above 209 therefore no alarm was given until I noticed low power.  Fortunately it looks like the block is okay and I'm having the stock heads rebuilt and new head gasket installed when it gets here.  I had the coolant temp sensor in the 5/8ths hose near the fire wall but I'm removing it and installing the pressure sensor there.  I am going to mount the temp sensor in the top radiator hose.  I measured the radiator hose barb and it's 1 1/4".  Ebay has some aluminum anadized sensor adapters with 1/8 NPT in with 32mm hose attachments and clamps for $9 shipped.

 

Why are spec Miata parts suppliers selling aluminum temp sensor adapters for $50 plus shipping?  Is there a quality difference between the two that equates to a 500% price hike?  Also, some of the spec Miata suppliers are saying the 1 1/8" adapters are specifically made for SM... why is my hose 1 1/4" which fits perfectly onto the factory hose barb on the thermostat housing?

 

Also, I found what I think is the only hole in the radiator where the massive (3"x1") dent is from the rock.  I used solder made for stain glass windows and a 100 watt solder gun with a large tip to solder the hole up.  I used no flux core solder and some flux paste get a good solder.  This solder doesn't flow like the stuff I use on electronics but seams to have done the job.  I am going to put it under pressure hopefully tomorrow to confirm it will hold but wanted to know what others have done and if they think this is an appropriate fix.  A radiator repair shop said they were just going to solder it so I figured why spend $75 for that when I had the supplies at my house for free.  Not trying to be cheap but as long as it's fixed that's $75 to go for something else... like more spares which I am more and more inclined to get a bigger spare bin and make those spares either really good used parts or new.  A worn out alternator doesn't do you much good if yours goes out on the track...

 

Also, what do you guys set your coolant pressure alarms on?  I was thinking 3psi min and 16 psi max (have a 16psi cap)

 

 

[Dan S]

So nobody has an opinion on why some are $10 and some are $50?  There must be a reason other than having a Spec Miata label on them right?

[davew]

3 words

 

Made In China

[Dan S]

Also, it appears Mazda is not selling the head gasket kit as one part number.  Is all that I need to buy are intake/exhaust manifold gasket, head gasket, valve seals and valve cover gasket set?

[Dan S]

I figured this was going to be one of the responses.  While I don't doubt the lack of quality that comes from china I am more interested in why their aluminum adaptor would be much worse than ours for this particular use.  Could the quality of the aluminum really cause an issue in this case?

[Armando Ramirez]

My Longacre unit is 3psi

[dstevens]

I figured this was going to be one of the responses.  While I don't doubt the lack of quality that comes from china I am more interested in why their aluminum adaptor would be much worse than ours for this particular use.  Could the quality of the aluminum really cause an issue in this case?

China and cheap aren't necessarily synonymous these days.  Those adapters you see are cast by the thousands, tumbled and anodized very inexpensively.  Much less expensive than machining the piece from billet.  They are likely OK.  It's a part made for the tuner car set and not the race set  Wheeler's piece looks to be machined billet.  I'd rather buy from the race shop even for the extra cost of something like that.  First, you support the locals that are in a position to support you.  Second, if there is a failure, casting breaks, threads fail, etc your engine will quickly overheat before you know it and it's going to cost more than the 40 bucks you tried to save.  There are likely differences in material with the low cost part coming from low cost AL but that isn't as much of a cost differentiator than the scale and manufacturing operation.   Other things to watch out for on lower end fittings are dimensional tolerance and the quality of the machining, particularly the threads.  Those tuner car parts are meant for ECU sensors typically so it's best to see it they are deep enough or capable of housing whatever sensor your DAQ uses.  My guess is that it's probably going to work as long as the threads are correct.  if it doesn't you aren't out much.  In my case, even if it is a 10 buck part (which is not the case of a billet sensor housing) I'd rather give Wheeler the money and be done with it.

[Alberto]

Also, it appears Mazda is not selling the head gasket kit as one part number.  Is all that I need to buy are intake/exhaust manifold gasket, head gasket, valve seals and valve cover gasket set?

 

The entire engine gasket set is around $150-170.  The intake/exhaust manifold gaskets are metal so re-useable to some extent...

 

I'm running the coolant adapters from Advanced Autosports and am very happy with the quality. 

[Dan S]

EDIT:  The advanced autosport adapter will not work for me.  It's 1 1/8" and I need 1 1/4". 

 

I didn't think about the billet aluminum vs cast aluminum.  I figured they were all cast but with just varying qualities of aluminum.  Thanks for the heads up!  I will be purchasing the billet one now for sure. 

 

 

 

Sounds like it may be cheaper to buy a used engine than to rebuild head and replace gaskets....  I'm planning on using this uncompetitive sm for seat time and to start racing with.  Eventually I'll either attempt to make this one competitive or buy another that already is competitive.  I will have to ponder on this....

[Jeff Wasilko]

I had a VDO pressure sensor (2-wire resistive) that would overheat and start reporting 0 psi, which is useless.

 

I switched to a high-quality pressure transducer from Ashcroft (3-wire) and I've had no problems. It was rated into 240-250 degF.

 

I use 4 psi as my warning point on my MXL.

[fotostars]

I never thought of overheat of the sensor, but that could explain why my resistive 2 wire pressure switch from the Longacre kit would be erratic ??

Maybe do a really good pressure sensor instead and wire it to my traqdash instead of just a pressure switch to an idiot light...

Uhm....

[Jeff Wasilko]

I never thought of overheat of the sensor, but that could explain why my resistive 2 wire pressure switch from the Longacre kit would be erratic ??

Maybe do a really good pressure sensor instead and wire it to my traqdash instead of just a pressure switch to an idiot light...

Uhm....

It could be. My sensors are in the heater core bypass, so it's close to the headers.

 

The Ashcroft sensor I have is from the G2 line, 30psi. http://www.ashcroft....-Transducer.cfm

 

The guy I talked to at Ashcroft said they do lots of business with race teams. Their stuff seems solid.

[fotostars]

It could be. My sensors are in the heater core bypass, so it's close to the headers.

 

The Ashcroft sensor I have is from the G2 line, 30psi. http://www.ashcroft....-Transducer.cfm

 

The guy I talked to at Ashcroft said they do lots of business with race teams. Their stuff seems solid.

 

I ordered a Ashcroft G2 , 30psi. Will be installing it before my next Week-End. I have one spare input on my Traqdash to monitor and throw an idiot light!

[fotostars]

Sounds like it may be cheaper to buy a used engine than to rebuild head and replace gaskets....  I'm planning on using this uncompetitive sm for seat time and to start racing with.  Eventually I'll either attempt to make this one competitive or buy another that already is competitive.  I will have to ponder on this....

 

BTW, if you're rebuilding the head, you just get this set from Mazda: 8AN2-10-235A , it has the head gasket, cover gasket, cam seals, valve seals, intake and exhaust gaskets and a few other bits for ~$50...