Referring to my 400G block, 69 442. I don't remember ever experiencing an engine get so hot to the touch as fast as this one does. Normally, I wouldn't think a lot about it, however I've been trying to run down a strange hesitation issue (albeit half heartedly) that only seems to rear up when the air temp is high. I tried to dial the timing back a tad the other day and the stumble got worse, but what really made me pay attention to the engine heat was when I fired the car up to get it out of the garage, it was maybe running for a minute and the engine was stupid hot (externally). Even once I parked it, after a few hours it was still a scorcher trying to get the air cleaner off, and the next morning there was still some heat coming from the intake.

I reset all of my adjustments yesterday to the point where it runs as it did before I put my hands on it, however the heat is still bothering me. The one thing I haven't checked is the fan and have heard that when the fan clutch goes bad, it'll whine as the RPM's go up (which I have that issue). The engine doesn't overheat though..and as far as the cooling system the only issue Im aware of at this point is the fact I've still not installed the lower radiator hose spring.

Am I freaking out over the engine being so hot, or is there more to be concerned with? Could the 2 issues (stumble & heat) be related?

Thanks in advance.

 

Dialing back timing can make it run even hotter. Was it pinging or anything? Fan clutch should have resistance as you spin it cold. If it freewheels alot replace it. As for the stumble it could partially be the crappy gas we have today.

 

Excessive engine heat can cause a stumble, or even a no start condition. Do you have a coolant temperature sensor or just a dummy light? Has the light ever illuminated, or have you ever overheated the engine?

 

No, it ran great..which is why I was hesitant to blame the stumble on timing.

I can spin the fan by hand, but it doesn't spin long after I stop pushing it.

Regarding the gas, it's pump 93..but then again, its pump 93..ha.

 

Dummy light, which only goes off when first starting and shutting down the engine.

The only time it's ever had an overheating issue (other than when I didn't have the correct radiator cap and it'd just push fluid out of the overflow) was shortly after first fire-a freeze plug fell out. I was not around when that happened, though I don't expect Dad would've driven around on it. Since then however, the only issue being that radiator cap pressure problem which the coolant level never got below 2/3rds in the radiator.

 

Without knowing the engine temp, your guess is as good as ours. I will say an engine driven for more than 30 minutes will burn the skin off of body parts.

 

look again at your clutch fan, it should not spin even once

 

so while cold, engine off, I shouldn't be able to turn it with my finger?

 

Should feel a considerable amount of resistance
Should not freewheel.

 

there's some resistance. I can spin it and as soon as I let go it comes to a relatively quick halt.

 

To test your fan clutch: with the fan clutch properly installed on your car, turn the engine on to warm it up. Once warmed up, stand where you can see the fan, and turn the engine off. If the fan goes around more than 1/2 a revolution, you probably need to replace the clutch.

 

If you think it is suspect just replace it, they aren't that much. I had two different "good used ones" on my car that felt like they were fine and it always ran hot. I bought a brand-new Hayden heavy duty fan clutch and problem solved.

 

Yeah, I would replace it. I would add a gauge or at least check it with a temp gun.

 

Also, I would suggest buying a hand held infrared heat sensor so you can find out exactly how hot it is getting.

Edit - olds 307 and 403 beat me to it!

 

Very good advice here. Oldsmobile's do like to run hot if not cooled correctly. My 70 came with a non clutch four blade fan. It ran crazy hot. I changed to a clutch fan. A clutch fan cold should give you some resistance. A clutch fan has a "thermostat " in the coil on the fan. If a clutch fan spins freely cold the "clutch" part of the fan is toast. Think of it as an AC compressor that kicks in when you turn on the AC. A clutch fan with the clutch burnt out does not spin like it should with the engine. It free wheels. It doesn't grip. Just my two cents.

 

Alright, just got home and did my best fan checking without losing digits..

When I spin it by hand, there is quite a bit of resistance. Also, I fired the car up and let it run for a few minutes..then positioned to allow myself to shut the car down and see the blades per above and it stopped almost immediately.

I think I am slightly advanced though (which is irritating as I thought it'd run enough to get up to temperature when moving it back the other day) as it's getting to be a little more sketchy to fire off. I can probably grab an infrared gun from work one night and see if I can get a reading.

 

I just popped out to my car. Been in the garage all day, its currently 90 F out there. Started the car. After 1 minute, the cylinder head (aluminum) was 149 F. After 2 minutes, the cylinder head was 176 F. Valve covers were still at 90-95 F.

Is your vacuum advance hooked up and if so, is it hooked to manifold vacuum?

 

yes, manifold vacuum.

 

How much vacuum advance do you have at idle?

 

advance? Or vacuum in general?

Last I looked I was around 8". Long story short, that's gonna be about the best it'll be.

 

I'm asking how much vacuum advance do you have at idle? The difference between your timing with it hooked up and with it disconnected (obviously plugging the line).

 

Oh..im following now. I'll be honest, I'm not sure. I've always timed with it unhooked (both initial and mechanical)

 

I'd recommend checking. First, it may not be functioning, even when hooked up. Second, there are other canisters out there that can potentially offer more vacuum advance. Since vacuum advance doesn't impact cranking, you get that extra advance "free". Obviously, you still need to be careful to avoid pinging, but if the engine wants more advance, that will give it more without hard starts. .

 

I think he is asking how many degrees of advance are you running at idle with and without vac advance. I also don’t remember if you are running a small cap distributor or a HEI style. with the HEI you will need to run more advance at idle as it doesn’t advance as much through the upper rpm range.

 

I'm running the original distributor, which was restored and recurved for the engine. I can grab the card and tell you how much advance it's claimed to have, but I'm not sure thatd answer the question.

 

infrared temp gun is your friend..

 

There is a procedure in the manual for testing a fan clutch that doesn’t involve losing fingers, or even getting your hands dirty.

Grt the engine hot. Put a blanket over the front of the car to restrict airflow. Rev the engine to 2500 rpm and old it there. If the tan clutch is functioning correctly, you will begin to hear a noticeable roaring sound, and can probably see the blanket sucked into the grill. Remove the blanket, let the engine idle, the roar will disappear after a minute of 2.

Without a real gauge, you are just guessing at the actual operating temp.

 

My Olds sat once at a car show running as my wife left it- ... yep... well anyway, it overheated and never had before- of course in front of all the town. Anyway, I checked the fan clutch and figured that was the problem. I bought a cheap generic fan clutch online. It Roared like a sun of a gun, I hated it but it did keep car cool at idle. I hated the roar so I bought a more expensive Hayden brand fan clutch- it also roars so that is how it is now. noisy but it works.

 

Drove it into work this morning, that way I can have a better shot at borrowing the temp gun in case they'd rather not let it leave the premises (completely understandable)

Ironically, it started and ran fine into work..which has been the MO when the air temp is down. So while that doesn't solve anything, it does continue to make me think it's a heat problem. Whether it be timing with air temp, carb being too lean, whatever.

I'm super annoyed about it though as I was living with the slight hesitation until I could get the exhaust done and have it put on the dyno to be tuned via wideband..but now I'm back to focusing on it and not stuff I should be focused on..ha!

 

Yes.

 

ha! I'm okay with that.

That gets me back to the stumble, which can be something as simple as a carb adjustment..which started this rabbit hole to being with.

 

Use a timing light to figure out the how much the vacuum advance advances the timing. No need to change the idle RPM. Hook up the timing light and start the engine. Note the approximate location of the timing mark (will probably be past the end of the timing tab), then disconnect the vacuum advance and plug the hose. Now the location should be on the timing mark. Get an idea of how far they are from each other and estimate the number of degrees based on that distance vs the number of degrees per inch on the timing mark. With 8" of vacuum at idle you need a special vacuum canister to give you enough advance. Hopefully they dialed in the distributor correctly, but this will check.

 

I've got a dial back light, so I can just read numbers with that. I'll run out and grab the dist. card shortly, but I'm doubting it was rebuilt with taking such low vacuum into account as the expectation with everyone was to have "normal" vacuum readings (16hg range)

I did put a quarter turn more fuel in the mix screws the other day, and it seemed to run a bit better..that is until I went from just cruising to really getting on it. Then afterwards, the stumble from a stop was back..which brought me back to-is the lower hose collapsing creating extra heat to the point where it's starting to boil the fuel at idle/low draw situations.

Exhaust/tune can't come soon enough..ha!

 

Update..dist. card

 

That could be your problem you are missing the 14 degrees vacuum advance. They may make a different advance that can provide it at that low vacuum.

 

interesting .I may have to track one of those down.

Thanks.

 

I agree. When my Cutlass had to be emissions tested I would disconnect the vacuum advance and the engine would run hotter than normal. After the test, I’d drive around the corner, reconnect the vacuum advance, and the coolant temps immediately decreased.

 

…would probably be good to actually check whether it’s a problem before spending money on parts you may not need. Checking timing with and without vacuum advance is incredibly simple…

 

I don't disagree, and more than likely will still do this prior to. However after having never heard of it before, then doing more research on it.. it does make sense.

 

I guess I don't see what the hold up is. I recommended you do this back on Monday. Are you not with the car? I literally pulled the distributor out of my car this morning to check the wear on the distributor gear and had to retime it putting it back in. Took less than an hour. You don't even have to pull the distributor.