Help me with fixing car

[Richard]

Part I

Scenario: 1992 Mazda Miata, 177,000 miles approx. Very loud, intermittent “squealing” noise in engine compartment.

Symptom: Thought was belts, replaced, still squealed. Decided it was a/c clutch so I removed belt for a/c unit... same noise, so that rules out a/c unit. Concurrently, the engine overheats while say, at a drive through with 5 cars in line. The temp gauge goes from roughly 1/3 to 2/3’rds range from time of ordering to pickup window. Hmm, WATER PUMP. So, I remove front of engine, replace water pump. While in there, I go ahead & replace timing belt and put new antifreeze in system.

Noise has GREATLY abated...but is still there, and further, is there when turning a/c on. Turning a/c OFF seems to help. (again, this is an intermittent noise)

Now, my deductions are that the (original) timing belt tensioners are probably worn out and new belt has them running tighter, hence, lowered noise... further that the turning of a/c to on.. changes tension enough to bring back noise.

Any merits to my logic?

It might be good to know that the nose is intermittent. There are times...well, MOST of the time in fact, that there is NO noise. But when the squealing is there, my word, it is gawdawfull.


Part II
With my engine temp quickly running up to the hot range just waiting on a bacon/egg biscuit in the morning, I deduced my thermostat is likely only partially opening, sooooo the other day, I replaced it also. Well, seems my temp gauge STILL races to hot today, even AFTER the new thermostat. So, new pump, new thermostat, system has been “rinsed” out with several flushings of clean water, though not “forcibly” cleaned and I’m still getting this over heating issue. (the radiator seems to be clean on a visual inspection and the fans do come on)

I’m lost. Any thoughts?

Thanks /w3tcompact/icons/grin.gif

edited as I noticed my title was truncated, so I changed it

 

[BHarrison]

On part I, I think you're onto something with the timing idlers. It is a good idea to replace them with the belt. The last timing belt kit that I bought from Napa came with the idlers.

Part II, I would look into the radiator opening, when the engine is at temp, and see if the water is flowing well. If not, there is a restriction somethere. When it gets hot, do the fans stay on, or do they cycle. Cycling meaning that the water temp is coming down, staying on meaning that something is heating the water beyond the capability of the fans to bring the temp back down. A cheap tool to get would be a back flush kit. This will help you in a couple ways. You'll be able to force water in a reverse flow through your components, and you'll be able to introduce cold water into the system which will aid in the troubleshoting of there possibly being a restriction somewhere. BTW the backflush kit is nothing more than a hose that goes inline with your heater hose, and has a tee that allows you to thread a garden hose to it.

So what you need to find out is, is the water flowing well, or
barely flowing?

Another good thing to find out is where is the temp sensor in relation to the thermostat? (and in relation to water flow) I dont have alot of experience with Mazdas, so forgive my ignorance.

 

[IndianaPaul]

Richard:

Not familiar with Mazada; however, might want to check the fan motor/clutch to make sure it is still working. Sounds similar to problem I had with both a ford and gm a few years back. Temp was fine as long as I was tooling down the highway, but minute I got in slow traffic or a drive up, presto, temp started up. Pretty much changed everything but water pump before it dawned on me that I was never hearing the fan run after shutting cars off, or when idling with windows rolled down.

Paul

 

[BHarrison]

Paul, the Miata has a sideways 4. Electric fans.

I know, I have to shift cerebral gears too when I go from working on a truck to a front wheel drive car.

 

[fishman]

I agree, those electric fans tend to burn out with regularity. Not too much problem usually, but on a Plymouth Grand Caravan I had it was a different story. The fan motor burned up and melted the entire wiring harness!/w3tcompact/icons/shocked.gif I was able to limp home, but just barely.

The fan in my Dodge Neon crapped out after 3 years of ownership as well. Hey, I think I notice a pattern here!

Anyway Richard, those motors are cheap and easy to diagnose and replace. That's where I'd go next.

 

[Richard]

Ben: I’m hoping with the idlers, I can replace them without having to take ENTIRE front end off again... sigh.. will try anyway...SOMEDAY soon. /w3tcompact/icons/grin.gif

The water does seem to be flowing well when all is up to temp. When I filled it...car was idling.. then as warmed up the water did appear to flow absolutely fine ...then the water level lowered.. my presumption there was that the lowering of the level was the engine block filling with water from the draining I’d done, so I just topped off. I did this procedure several times as I was “rinsing” the system. Finally, I simply put the required amount of antifreeze in to “dilute” the water to the 50% mark.

Paul/Ben: The fan did (finally) appear to cycle on. I’d wondered about that as it was idling, then all the sudden... it came on. So either it’s working fine, or maybe it’s working intermittently. Given I saw it on, I gave it no further thought. Might bear some closer inspection.

Paul: Electric fan as Ben mentioned. The engine however, is a “normal” front to back 4 cylinder, as the car is rear wheel drive. The engine is not transverse mounted.

Fishman/all : again, since fans (actually, I only witnessed ONE of them working it has 2) worked, I dismissed them all together. Since I only witnessed ONE of them working, it indeed might make sense of all this.

Thanks to you all.

 

[s1120]

Ok, I will try to help. I work in a Mazda dealer. First, very little goes wrong with these cars, so there is nothing common. First thing I would try, is remove all drive belts. Does the sound go away? If so, you may have a drive belt ideler going. Secound, unhook the elect fans. The secound should only come on with the AC on. I have seen this one go bad. Third, put new ideler pullys on for the tbelt. They don't go bad often, but with that kind of miles, anything can go wrong. Report back any findings, and we can go from there.

 

[s1120]

Oh, one more thing. I see you put a new tstat in it. Did you use an OE Mazda tstat? If its an aftermarket one, get it out of there. Aftermarket tstats DO NOT work in Mazdas! I don't know why, but we get them in all the time. And it IS common for a tstat to go on a Mazda, so thet may be your problem. An OE tstat is not that pricy, about $15.oo, and it comes with a gasket. Good luck.

 

[Rowski]

Richard.

Does the nosie happen hot or cold? Can you duplicate the problem? I did find a TSB #003/94 that concerns a revisied idle pulley(s) for the timing belt. Also does the noise happen during stand still, on the road, or both. Does the noise change when the engine speed is increased?


As for the cooling system (overheating) I almost bet a dollar you have air in the cooling system. It can be a real PITA to get out! It can take a while to get out. I have found the one (of many) ways to get the air out is to jack up the front of the car so the coolant filler is higher than any other component of the cooling system. As alway keep safety in mind.

Also use Mazda OE stuff. I've had troubles with the aftermarket stuff. Like the t-stats not working and water pumps that have the wrong impeller, etc.

Let me know the answer to the questions above.

 

[s1120]

<font color=red>Also use Mazda OE stuff. I've had troubles with the aftermarket stuff. Like the t-stats not working and water pumps that have the wrong impeller, etc.</font color=red>

Oh Ya. Got to use OE. Elect stuff most of all. We had a 626 in that some one put an aftermarket alt in, Tosted the engine control unit, and burnt up some of the harness. The $100 the guy saved cost him over $3000.