85CutlassSupremeInSC

I know overheating topics are covered ad nauseam on car enthusiast forums, but my situation may have a few wrinkles, so I'd like to get more input. At this very moment in time, I'm leaning towards installing a high volume water pump, but I'll go through what I've done up to this point so that I get better feedback...

My 85 Cutlass had a 307 being cooled by a stock clutch fan and the stock 3-core radiator. I decided to upgrade to a decently upgraded 350. Brand new motor. The engine is installed and running. The first thing I did after I got it running consistently was install some (AutoMeter Phantom II) manual gauges, temperature and oil pressure. I was still in the process of breaking the motor in, so I drove it on errand runs in the local area, no further than 4-5 miles and I noticed (by the gauge) that the block was getting up to 240+. After acquiring a second means of measuring the engine temp, it was confirmed that the gauge was bad. The gauge was reading anywhere from 10 to 30 degrees higher than the actual temp. That means the day that I thought I was reading 240, the actual temp was about 210 to 220. After that ordeal I purchased a Mr. Gasket radiator cap with a thermometer on the cap. 220 is nowhere near where I'd like it, but not 240+ either. I have a 180 stat installed, so I'd believe my running temp should be 190-200, if I'm not mistaken.

Prior to confirming my bad gauge I had the radiator professionally flushed and tested and I replaced the fan clutch. I even went ahead and replaced the upper and lower radiator hoses since the car has been sitting for about 5 years. After all that the car is still getting to 220, so I'm guessing the next step is a high volume water pump...

Anyone have any other suggestions?

Almost forgot. I know that my engine timing is off, but I don't think it's not so far off that it should affect my engine temp this much...

88 coupe

What does that mean?

Unlikely that it's new. I will assume, it is a "fresh rebuild".

What do you know about the competence of the "rebuilder"? What piston/bearing clearances did he/she use?

Stop and go? What speeds? How long were the stops?

Should maintain approximately 180° if the system is working properly.

Correct it.

After you have it tuned properly. take it for a cruise, at highway speeds. Does it get warmer, when under load? Cooler when there is no load?

These are questions that should that should have been answered, before you started "fixing" it.

Norm

85CutlassSupremeInSC

I know the answers to those questions, hence my dilemma...

If I knew how to apply the answers properly, I wouldn't be here for advice...

But since you took the time to ask, I will give you the answers...

As far the timing is concerned, that is beyond my area of expertise and I thought I'd see to it that I focused on getting the temp down first, even though I know the 2 are related...

"Decently upgraded" means upgraded cam, intake, new headers, heads, new timing chain, and new 750 cfm carb...

Competence of engine builder? The machine work on the block was done by a reputable machine shop. Customers come from over 100 miles away to see these guys, if that's an indication. I've never heard anything but rave reviews for these guys. I've also had them do work on another 307 for me so I trust them. Couple that with the fact that the machinist is a professional associate of my engine builder who happens to be my uncle, and someone who builds engines by trade. I'm pretty confident in the block. The pistons were bored .30 over.

I guess you could say the errands were stop and go, but there weren't that many stops, maybe 2, and top speed was about 45.

Even though it's only partially tuned, the temp still drops when driving at highway speeds. It only gets warm when I'm stopped, in the yard or at a stop light, doesn't matter. Once I start moving again, it drops, as it should...

Lady72nRob71

Since it cools down at highway speeds, you seem to have an airflow issue.
Does it cool down to about 180-190 while moving?

Do you have the fan shroud installed? Is the new fan clutch working correctly? At idle while running hot with the hood open, there should be a good blast of hot air from the fan and there should be a distinct roar of the fan moving lots of air. Standing at the fender looking towards the fan, the hot air blast should be blowing your hair and causing you to squint your eyes. I take it this is a thermal type fan clutch (coil spring at the front)?

Do get you timing set soon. It may seem involved at first, but it is not too difficult to do. It would not cost much for your mechanic to do if you decide not to do it yourself. This could have some effect on your cooling...

85CutlassSupremeInSC

Now that I think about it, it did cool down to about 190-200 after I drove it at 60 for about 11 miles. The fan shroud is installed and the fan clutch seems to working properly. I did notice positive results after I exchanged to old one for the new one. I noticed the hot air blast yesterday. It seemed a bit warmer than I would like, though. My upper radiator hose was under a lot of pressure too.

I hope to get the timing set soon, but that is another issue for another thread. I think I'll post it after I finish this one. The reason I was leaning towards a high volume water pump is because when I was getting my engine built I ran into some problems with bad heads. The machinist felt bad about it so he gave me some performance heads. I took them but my engine wasn't spec'd for them. I think they raised my compression ratio and are pumping out more heat than I anticipated...

Thanks for the reply!

Olds64

I wouldn't think you would need a high volume water pump. The coolant has to have enough time in the radiator to cool off anyways. If you didn't do any major changes to your engine except a mild cam and headers that shouldn't effect the engines cooling ability too much. Definitely get that timing set FIRST and then worry about your cooling. You can't tinker with the cooling system and expect results if the timing isn't right.

85CutlassSupremeInSC

Sounds like good advice. I'll try it since I'll save money if it works...

Thanks for the responses...

88 coupe

And that of your machinist/engine builder?

Is that what your machinist/engine builder told you?

I think I will be setting this one out.

Norm

85CutlassSupremeInSC

I meant cylinders, but thanks I'd appreciate it if you would...

85CutlassSupremeInSC

Update:

I spoke with Summit Tech Support and they gave me the information I needed to get my engine set to the correct timing for my cam. It stalls a little when I put it in gear now, but that's another issue. The timing is set and it still runs warmer than it should, it tops out at 220, no warmer, tech support said the motor should be running at 180 with my setup. I then went to speak with a few more mechanics, both professional and shade tree. The consensus was for me to upgrade my radiator to a 4-core...

I guess I'm going radiator shopping tomorrow...

Olds64

After setting the timing did you set the idle speed and idle mixture screws? If your car stalls when you put it in gear that is an issue you need to fix before tackling the overheating. Hopefully your idle speed is just set to low. Have those two adjustments done and get back to us. Good luck!

85CutlassSupremeInSC

Thanks for the support, Olds64...

Update:

I'm still plugging away at this overheating issue. I took Olds64's advice and tried to address the idle speed and idle mix issues, only to find out that I now have a vacuum leak somewhere that is affecting my carburetor performance. It looks like I'll probably end up removing the intake manifold to either check or replace the gaskets. I pulled the carburetor to make sure its gasket wasn't damaged and from what I could see it is seated nicely with no leaks...

As for my heat issues, I spoke with 2 automotive cooling professionals. One was the gentleman that was responsible for rotting out my radiator. He informed me that the radiator was running fine with proper flow and that I shouldn't have to replace it. The second was a lady that's been working at a local radiator shop for years. She said that she'd be happy to sell me a new radiator, but that it wasn't going to fix my issues. She said that my 3-core radiator should be sufficient to cool my vehicle. The newer 3-cores aren't going to provide the amount of cooling that I desire. I then decided to install a flex-fan just to see if I could see a difference in temperature. No dice. It still got up to 220, so I didn't make any progress today. Tomorrow, I'm going to let the radiator man look at the car with the radiator installed and running. I'll be back to post my findings...

Oldsguy

find the vacuum leak before you do anything else, even remove the manifold. It may be a simple fix and is essential and primary to a good tune-up and can affect how well the engine runs.

Olds64

To pin-point that vacuum leak you could take ether (starting fluid) and spray it around the base of the intake manifold and carburetor while the car is running. If the idle changes then you know you found the leak. Be careful though, this is sort of a hill-billy way of doing it.

The correct way to do it would be to use a Vac-U-Tec machine that pumps smoke into the manifold through a vacuum hose. However, these are hard to comeby for the do-it-yourselfer and not very common in today's repair shops.

citcapp

WD40 works for this also and has a lower flash point then the starter fluid

tclaemont

I am going to suggest a smaller carb while you are at it.

What you are experiencing is a combination of factors that all affect your engines ability to run cool. I was willing to bet that the timing was a big part of the equation. Do you know what the timing is set at now? The factory settings are out the window if the cam has been replaced, so if you are setting it at the typical 5 to 8 degrees you may still be off base. Small changes in timing can and do have a big effect on the cooling of the engine.

Other things to consider: Is the lower radiator hose collapsing, or otherwise obstructing flow? What are you using in the radiator? Antifreeze? Tap water? Distilled water? Since you have likely drained the radiator a tme or two, is the coolant clean or is it picking up junk while in the system? What does your oil look like? Is it clean? If it is dirty after a short time it might suggest a bigger engine problem.

85CutlassSupremeInSC

Update:

Today I attacked the vacuum issue. My father and I pulled and replaced the intake gaskets. As it turns out the old ones were improperly installed, but I'm not so sure that was the issue. After we put the intake back on and everything back together, it still ran a little rough, but the carb is getting great vacuum, better than before. It almost sucked my finger off and if you pull the vacuum advance line you can hear it sucking over the roar of the engine. I am starting to lean more towards the distributor being the vacuum culprit.

tclaemont:

My timing is set at 10 now. Summit said it should be set anywhere from 8 to 12. They also said that the carb should be able to handle my set up with ease.

The lower radiator hose isn't collapsing because I've made sure the system had plenty of water and I made sure it is one of those really thick hoses. Plus that's where all my water resides as I full up the radiator, so I'm sure that's not it. The top one isn't collapsing either, not with all that pressure. In the radiator I am using antifreeze and tap water. The coolant is clean and so is my oil. The oil was the first thing I checked when I started having these issues, and I checked it again today.

I appreciate all the input you guys. At least I'm getting ideas on what to pursuit next. This really has me stumped...

85CutlassSupremeInSC

I've been soliciting a few other people for advice and the going consensus is that I should remove my thermostat and see what kinda temperature results I get...

Olds64

You can always take the thermostat off and drop it in a pot of boiling water to make sure it opens.

85CutlassSupremeInSC

Well, I've changed the thermostat once already, so I doubt that is the problem, though doing what you suggested would give me confirmation...

Olds64: I just realized that you live in Lawton. I used to live in OKC. I was stationed at Tinker. I used to come to Lawton to party with the Army girls at Ft. Sill...

As a matter of fact, I bought my Cutlass there and drove it to SC after I left the Air Force...

85CutlassSupremeInSC

Well, I have to go out of town for business travel. I won't be back under the hood until Tuesday, so my quest to extinguish this problem will have to wait until then...

Olds64

Lawton is a good place. I came here with the Army and decided to stay.

Now if I could just find an awsome car here like you did. Oh wait... there is one in my garage!

85CutlassSupremeInSC

I'd be happy to help you get rid of that problem!

Olds64

I've had it for sale for the past few months. Nobody is too interested in it since it doesn't run really well. Oh well... I will get my 455 in it someday... maybe.

https://classicoldsmobile.com/forums...s-98-sale.html

85CutlassSupremeInSC

Update:

I finally figured out my problem!

It turned out to be the fan blades. I had the wrong fan installed on the engine. The fan blades were angled in the wrong direction and they were pushing the air out the engine compartment instead of pulling it in...

The engine now runs at 170, and I have a 180 thermostat installed. I'm not sure if I now need a higher thermostat, but it is at least drivable....

71 delta88guy

Glad you're all fixed. If only people would ask questions related to the topic and not nitpick posts perhaps we might be of more use to those in need. Not pinpointing anyone in particular.

85CutlassSupremeInSC

Thanks, man...

I catch your drift...

Lady72nRob71

Hey - glad you got it fixed!
I would say leave the 180 t-stat in there. In very hot situations (like in Dallas in summer) it would have no problem staying at or above 180!)

One thing I will say... My new fan clutch was disengaging at about 150 and engaging at 180. I would hear the roaring sound even doing 55 on the highway. I took it off and gave a very SLIGHT tweak in the coil spring in the front to loosen it oh so little. It now runs closer to but a often a little higher than 180.

Olds64

Glad you got it fixed. I wonder how the car ended up with the wrong fan on it?

88 coupe

I am happy that you solved your problem without our help.

Common novice mistake. With more experience, it becomes less common.

In person, most anyone with diagnostic experience, would have recognized it as soon as they looked at the fan.

Not so, on the internet. To accurately diagnose a problem, such as this, a lot of questions must be asked and answered. If, because of ones fragile ego, he/she cannot supply straight answers to those questions, the "system" falls apart.

Unless it is malfunctioning, no thermostat will cause an engine run at a higher temperature than the rest of the cooling system allows it to. If it runs at 170° with a 180° stat, it will run at 170° with a 195° or with a 1,000° stat.

One way to make it run warmer, would be to exchange the radiator for a smaller one. Another would be to retard the advance, a couple of degrees

BTW: After the first line, this post is "pinpointed" at anyone who reads it.

Norm

88 coupe

Were there any, in this thread, that were not?

If they exist, post an example, so that everyone will know exactly what you are referring to?

I believe, the "nitpicking" you refer to, is a vital part of the diagnostic process. If not (or, if your advanced chronological age and your many years of experience "as a mechanic" have given you a different opinion) perhaps you can tell us, why it is not.

On another note:

I did notice some bogus advice was given due to the lack of pertinent questions.

Norm

85CutlassSupremeInSC

Very valid question...

While I was troubleshooting this issue, I had my car parked at a family member's home. He's putting a 60-something Nova together so he has all types of miscellaneous parts all over the place. I know for a fact that there were at least 4 fans out there and there is no telling how many times I've taken the fan and fan shroud off...

I guess I picked up the wrong one...