Z28_1991_Camaro

I am trying to transfer ownership of my car from my dad's name to my name so I needed to do a safety check and emissions test.

I brought my car yesterday and the engine was almost at operating temperature by the time I got there. I don't currently have a thermostat installed so it takes a while to actually get up to temperature. They did the safety first so the car sat for a good 30-45 mins. I'm wondering if that was enough time for the engine to cool down too much?
I passed all the categories without even coming close to any limits except for the HCC, I failed by 65ppm. I passed the HCC at idle but failed the driving test.
Could then engine not being at operating temp have been the reason I failed?
I replaced all the emissions related items last spring except the egr valve which I replace this past weekend. So basically my plugs, wires, cap and rotor, o2 sensor and cat are all a little more than a year old and my egr valve is brand new.

Any suggestions as to what I could do to pass the test?

DIRTY JERZY

Put in a thermostat

Z28_1991_Camaro

The engine overheats when the thermostat is in

$750 L98

The you have a problem causing overheating that needs to be addressed, in fact whatever is causing it to overheat is likely your really problem.

Never try to solve a problem by removing parts that should be in a properly working car.

Z28_1991_Camaro

Let me explain a little further.
I swapped my 305 to a 350 several years back and ever since, the engine has always ran hot on hot days but was fine when it was below 85-90 degrees outside. Even on those hot days, if I was travelling faster than 80km/h the air dam was more effective and the engine would cool down. The difference was on those hot days with the thermostat in, the engine got hot very very fast to the point that it was much hotter than I liked, with the thermostat removed it took a long time before it got hot and a significantly longer time before it got to a point that I would start to be concerned about. So with it removed I was able to drive the car without it getting too hot.
Last fall I upgraded to an aluminum radiator and I wanted to make sure it didn't overheat with the new rad. So before I put the thermostat back in, I need a hot day to come around so I can see how hot the engine will run. If the rad does it's job then I plan on putting the thermostat back in.

I have passed emissions tests in the past with no thermostat in so I think it is unlikely that is why I would be failing the test especially considering I passed every category with flying colors except the one that failed

RED86Z28

The car was probably too cold to be in closed loop. You should put in a thermostat and try again.

DIRTY JERZY

Did you bleed out all the air in the system when you did your swap? trapped air in the cooling system will make the t stat not work.

$750 L98

Are you running a 350 PCM? Are you running a 350 top end? (injectors) When you say it got hot, how quickly did it get hot? Quickly overheating can be a symptom of a blown head gasket.

These cars will not get that hot with proper maintanence, mine never saw over 210*, if you are using old/wrong injectors you will have missfires that will increase HCC.

I also didn't mean that not having a thermostat was the issue, rather the overheating is the issue. If it overheats with a thermostat in it, something is not working like it should. I'd put a thermostat back in and try again, if it overheats you have a problem, if it runs up to 210-235* that's normal, especially with stock fan settings on a hot day.

Z28_1991_Camaro

The air was bled so that is not the problem.
Like I said, I want to see how it reacts to a hot day 1st before I put a thermostat back in.

When I originally did the swap, I kept my original injectors and I had a chip made for the 350 and to use the 305 injectors. I have since put in the 350 injectors and had the chip reprogrammed.

With the old rad and a thermostat on a hot day, it would get up to operating temp in a matter of minutes and then it would keep climbing slowly if I was driving, but very quickly if the car wasnt moving. One day I had just got home and I sat in my driveway just watching the temp gauge and it just kept getting hotter and hotter, I watched the temp gauge increase until it was near the red line. This happened in less than 5 minutes Id say. It was at that point that I took the thermostat out and it resolved that issue to the point that the engine never got that hot again.

$750 L98

Sounds kind of like my Formy after I blew the headgasket, only way to keep driving it was without a thermostat. Have you watched the coolant flow through the radiator? Does it bubble up, froth, or look like it's spitting it out violently as it circulates?

If it overheats that quickly something is very, very wrong.

Maybe something is causing it to lean out to the extreme, which would cause missfires and high HCC. Dead O2? Does it show any codes? Check to make sure the SES light isn't out. Something that catastrophic should set a code.

Regardless I wouldn't drive it until the issue is resolved even if it runs ok without the T-stat, if the problem is related to fueling you could easily melt the pistons or tear the headgaskets/heads up pretty quick, might not make it more than a few months.

I think I made it on mine about 4 months after it started doing this.

Not trying to be impossible to work with or anything, but not having the car for a week or so and spending a couple hundred on parts is much better than a full blown $2,000+ rebuild.

DIRTY JERZY

I agree. I would do a coolant presser test. Thats just where I would start.

Z28_1991_Camaro

Is there a way to check for misfires?

There are no codes.

The coolant flow seems pretty smooth, not really sure how I would describe it but not like any of the adjectives you suggested.

How do I do a coolant pressure test?

It only got that hot that one time. Could the water pump be a contributing party? The water pump is more or less the only thing I didn't replace when I swapped the engines only because it was only a year or two old at the time.

DIRTY JERZY

you would need a coolant pressure tester or you can take it to a shop its a cheap test.

Z28_1991_Camaro

What will the coolant pressure test tell me?

I drove the car to the bank today, it was a very hot day today. The temp was just over 220 while I was driving then when I got home I just idled in the drive way and it got up to about 235 pretty quick, then over a span of 5-10 mins it got up to about 240 where it seemed to peak.

That is too hot for my liking.

Am I wrong to believe that with an aluminum rad I should be quite a bit cooler than that?

I'm going to put a thermostat back in it tomorrow and see what happens.

xX89RSXx

iTrader: (1)

Is the fan working?

Z28_1991_Camaro

Both fans are working.
One of them is on at all times and the other comes on around 205 degrees I believe

Reid Fleming

iTrader: (2)

What figures did you get on the emissions test? What were the standards to meet?

I'm not so sure it's a head gasket. When mine went, the temp guage would go from 1/4 to the red zone in about 15 seconds. I'm thinking water pump.

What temp and humidity conditions are you experiencing in Ontario right now?

irock88

Every year the numbers for emissions test get tighter from the previous year.
In regards to your over heating issue both fans on should be more than enough to cool down the engine, could be the water pump, serpintine belt.
My HCC was also high so to correct this to bring the numbers to acceptable level my mechanic brought out a large cooling fan and placed it in front of the rad which passed emissions....barely

Z28_1991_Camaro

HC ppm: Limit = 55 Reading = 107
CO %: Limit = .31 Reading = .07
NO ppm Limit = 612 Reading = 268

The above #'s are the driving test at 40 km/h

HC ppm: Limit = 200 Reading = 110
CO %: Limit = 1 Reading .02

The above #'s are from the curb idle test

The weather yesterday had a high of 86 degrees. I don't know the actual # for the humity but it was not that bad yesterday.

If it was the head gasket, wouldn't my oil be contaminated with coolant? Because the oil looked fine when I did my last oil change.

timespy

Throw in a heated o2 sensor, make sure the fuel filter isnt clogged up. Do you have a nice fine misty cone from the injectors when its running? If its running lean you can perhaps trick it a bit by fouling an old air filter. That may get you by the test. When I hear stuff like this about emissions it makes me so happy I live in illinois.

Z28_1991_Camaro

Perhaps the most annoying part to the whole emissions testing is I don't think I have ever passed my 1st emissions test with my Z28. I maintain the car better then most people I know and yet none of them have ever failed an emissions test. Perhaps even more annoying is that I also have a honda accord which I have not changed a single thing under the hood on that car for as long as ive owned it which is about 2 or 3 years now and that car passed with flying colors, it even read "0" in two of the categories.

Anyhow, I read somewhere online yesterday, I cant remember if it was on here or somewhere else about measuring the external temp of the radiator to tell if the water pump is working properly.
So I did that and these are the #'s I got, I'm not really sure what they show exactly, maybe someone can clarify?

On the upper drivers side it was 125F
On the lower drivers side it was 120F
On the upper passenger side it was 110F
On the lower passenger side it was 120F

I also checked the rubber hoses, the lower large hose on the passenger side was 103F right next to the rad, a little farther away from the rad it was 150F.
The drivers side hose was 185F right next to the rad and about the same a little farther away.
The thermostat housing was 210F

RED86Z28

You say it runs hot but has it ever boiled over? What kind of temperature gauge are you using for reference?
Your numbers for the temp gun seem ok.

Z28_1991_Camaro

I don't think it has ever boiled over.
The temp gauge I'm using is the one on the dash. I checked the temp of the thermostat housing and it was nearly identical to the reading on the temp gauge so Id say its accurate enough.

I brought my car to have a diagnostic on it yesterday. The guy told me to change the catalytic converter. He did not seem convinced that the cat was in fact the problem. He didn't charge me for the test, he said change the cat and if it passes the next e-test then we can talk #'s.
The fact that he didn't charge me makes me believe he is just hoping the cat is the problem.

So I changed the cat yesterday and I discovered that the air tube was plugged. I'm not really sure what the air tube actually does, but I'm assuming it would have affected my e-test by being plugged. Could the fact that it was plugged have any contribution to the overheating?

Also, after removing the old cat I noticed it has some stuff shaking around inside of it. Any idea what that could be?

xX89RSXx

iTrader: (1)

I failed due to my cat also last year. It was the original falling apart inside. The stuff moving around inside is the honey comb. It is obviously not working when this is broken and deteriorated. As far as the air injection tube, I believe it diverts air only during cold operation, once the cat is at temp it does not do anything. I am not 100% sure though. I know if one is really clogged up you will feel a lack of performance.

Z28_1991_Camaro

I went for a re-test yesterday with the new cat on the car and it passed...just barely.
The HC ppm limit is 55 and it read a 53.

That still seams high doesnt it?

RED86Z28

There is something about the engine tune that is not quite right. Your HCs should be much lower.