Thread: New 350sbc do i have a blow head gasket? Or something worse..

Tweet

So I bought a 84 camaro not too long ago, the original motor had a rod knock it it so I bought a rebuilt motor (350 sb) and had it painted and dropped in aswell as the previous motor being pulled. I had my buddies dad and his brother drop it in at their shop on a weekend as a side job for them and they did it within about 6 hours i'd say. Well i have electric radiator fans that wont wire up to the ignition or else they blow a fuse, and sometimes my switch will go bad and burn up, then my fans shut off and over heat the motor.

This has happened twice and i have now bought a 15 dollar switch which hopefully will hold me off until i invest in better fans or a water pump mechanical fan (Which im unsure if I want a mechanical fan because they make your motor work harder). So I ovee heated it once and oil mixed with the coolant, but I had one of the guys come by and check on it and he said I was lucky as hell and that nothing was wrong with it. She started tigbt up, he topped off the coolant, and that was the end of that.

Now bare in mind with me that the motor, when turned off too quickly (since I got it) it will start banging and jenking around pretty roughly. So I seemed to have figured that out, i called a shop and the guy told me he had an old el camino that did the same thing. He told me put higher octane gas in and i have since, 91 sunoco fuel. And it has been alright since. Well the other week i over heated infront of my buddies house about a day or two after changing my oil, but my newer switch has gone out while I was idling infront of his house and talking with him. Fans stopped and before I know it resevoir cap shoots off and theirs oil in my coolant, i let it cool off for a little, topped it off with coolant and drove it home which was right around the block thank god. That night I went up to the auto parts store, bought a buncha distilled water, and 2 half and half coolant bottles and an expensive killswitch. So I came home, flushed the radiator, put the new switch on and she was running like new again. No engine sounds, no white smoke out of exhaust, no bubbles in the coolant. So for the next two days before I would drive Id turn her on, make sure everythings working,* made sure I wasnt loosing any coolant. And I wasnt. Then I started to drive her like I normally would again.


About two days ago I was driving two cities away to go pick something up from my buddies so I took her on I-94 and drove about 5-7 miles from home. When I got off the freeway, i was driving down the road and i got no response from the gas pedal, RPMs dropped to 0 and my motor started banging around like it would when I had the 83 octane gas in it, except this time it wouldnt stop, i popped the hood emediatly and hopped out, unscrewes the car battery and unconnectdd the wires out of panic. It didnt work! The key was out of the ignition and the motor was half ass running without the electric. Idk if this was the mechanics fault for not taking the required ammount of time to tune and make sure everythinf was running right on the motor or what. But the motor was running, all the pulleys were spinning, accept the motor was making banging noises,then after about 40 seconds it stopped and white smoke puffed out from the carb and through the air filter. Then the motor wouldnt even start! Oil mixed in with the coolant, but heres the catch. My fans were working! Everything was normal, water temp at around 180-200 and my oil pressure was between 20-40.* So i possibly had a blown head gasket already, because of the previous over heat at my buddies house, but i am not sure. Nothing like this has ever happened. Brand new motor, bout 5000 miles on it. It was rebuilt right, and no it does not have a rodknock or anything. She sounds beautifull when ran.

This whole situation is mind boggling me, no one else in history of the internet has ever posted about having this problem. I know now forsure that I have a blown head gasket, but does this sound like the engine has even more extensive damage? Did the mechanics who dropped this motor in not do something right? After they dropped it in for me they pretty much said come and get it and i picked it up and they never touched it again. They did somewhat tune her and ready the motor for driving, but idk whats wrong. (Motor was dropped in about 6 months ago, and I took it easy on her till she hit about 1500 miles, also had the car tarped up sitting in drive way for the last 3 months cause of winter)

First, welcome to Club Hot Rod! It's good to see you here.

I'd say let's start with some basics, Have you completed a compression check? Pull all the plugs, disconnect the power from the ignition, hold the carb ( if equipped) or throttle body wide open and insert a compression gauge in place of a spark plug, spin it with the starter and count 3 strokes, record the readings and let us know the findings.

It's going to be these basic tests, like compression checks and vacuum readings that will tell you the health of the motor.

Welcome to CHR!

Wow – there’s so many things in this post I could address, but I’ll try and focus on just a couple that may help you out. A stock 350 should run fine on regular gas – a tank of premium just before a long freeway trip may help clean things up a bit inside the combustion chambers but otherwise it’s a waste of your hard earned dollars.

You need to ditch the electric fans and find the proper shroud for the radiator and put the stock GM fan and clutch on your engine. It is the most efficient and best engineered combination of parts for all but the most radically built engines. The only time I use or recommend electric fans is for very specific clearance issues and then they still must be used with a shroud (see below). All electric fans that I use are on separate relays and draw between 20 and 30 amps. Trust me – the stock GM unit is the best combination for your car.

More important right now is the oil in the water – don’t know who told you, “You were lucky…” because in all likelihood that was the first sign that you’ve got a “not-so-little” issue. The oil and water systems are both closed loops and are designed to NEVER meet each other. At a minimum, you have a bad head gasket – worst case could be block damage, depending on how hot things really got. I’d recommend pulling the heads and seeing if that’s where the oil and water mixed – if not, obvious, there’s a crack internally that is allowing the two fluids to meet – not a good thing. Either way the engine may need to come out. Don’t be upset with the mechanic as this is in all probability attributable to the electric fans.

Sorry to rain on your parade. If you truly want to learn about your engine, I’d suggest buying “How to Rebuild Your Small-Block Chevy” by David Vizard and reading it cover to cover. It’s a $20 softbound book that you can buy from Amazon and it gets into the basics as well as advanced aspects of small block Chevy engines.

Good Luck,
Glenn

Originally Posted by 84Camaro

So I ovee heated it once and oil mixed with the coolant, but I had one of the guys come by and check on it and he said I was lucky as hell and that nothing was wrong with it. She started tigbt up, he topped off the coolant, and that was the end of that.

Oil in the coolant or visa versa is never good, you are not lucky as h-ll. Motor after running is not always caused by low octane, it can be a sign of tuning issues or more serious problems.

Originally Posted by 84Camaro

no one else in history of the internet has ever posted about having this problem.

You probably have a blown head gasket, continuing to operate it in this condition is causing more problems. Do a compression test and see which cylinder(s) are low. Fix your motor and tune it correctly. Wire your fans using a relay triggered by the ignition switch and eliminate your fan troubles.
On a street driven car mechanical fans and water pump are always your best choice, any perceived horse power gains using electric is quickly overcome by the alternators added current load.

And whoever wired your Camino obviously knew very little about wiring and unless you want to burn it to the ground I'd suggest than you get the wiring sorted out. As was suggested earlier get rid of the electric fans or start carrying a spare alternator with you. It's very hard, if not impossible, to tune an engine with it constantly over heating.

What would I do?
I'd pull both heads, strip 'em and have 'em magnafluxed for cracks. Then I'd put 'em in a mill and cut 'em flat, cause you just know they're all humped up and not flat anymore from the heat. I'd check how far down in the cylinder the piston crown is with the piston at top dead center and determine the gasket thickness I could run to make the best squish. Then I'd find all stock pieces and put a belt-driven fan back on the motor.

"I'm unsure if I want a mechanical fan because they make your motor work harder."

OK, here's what you don't understand. It takes a certain amount of work to turn a fan, whether it be mechanical work or electrical work. If it's mechanical work, yes, the crank has to turn harder to do the work. But in an electrical work system like electric fans, the crank also has to turn harder to turn the ALTERNATOR, which is supplying the electricity to do the work. So there's the same amount of work for the crank to do, whether you're cooling the motor mechanically or electrically. There is no free lunch.

.

Electric fans will always turn the fan at most effiecnt speed for airflow--crank driven fans aren't fast enough at idle and too much above cruise speed. An alternator will only put a load on crank when battery or accessories in use require power.

This guy has a wiring problem--------running his fan load thru ignition switch on terminal lets the rotataing fan create a reverse charge circuit that fires the ignition

Originally Posted by jerry clayton

crank driven fans aren't fast enough at idle and too much above cruise speed.

Use a steel 18", 7-blade fan with 2 1/4" to 2 1/2" pitch with a thermostatically-controlled fan clutch and full shroud. In my opinion, that's about as good as it's going to get. Lay the fan down on your bench and measure from the bench to the fan blade leading edge to find the pitch. If you really want to move some air, use a steel fan from an Oldsmobile diesel (1978 to 1985). You should be able to find them in old boneyards. (3 inch pitch).

.

"running his fan load thru ignition switch on terminal lets the rotataing fan create a reverse charge circuit that fires the ignition"

That's interesting, I wouldn't have thought of that.

If that were the case, then the symptom wouldn't have gone away when he changed gas.

He should wire the fan on a relay, sourcing power from the distribution node or block in his harness. Fused, of course.

Sorry for the book on this, seemed necessary.

CFM requires horse power, regardless wether driven by crank or electric (in our cars the electric is driven off the crank). Higher the CFM, higher the horse power required.

Electric fans use current to produce horse power. The more horse power (CFM) the circuit requires, the larger the load (current) demand will be on the circuit. If the load (current demand) is larger than the wire’s capacity or switch’s rating the circuit will fail at its weakest link. If the switch is the weakest link, the switch will burn up. If the wire is the weakest link, the wire will burn up and usually cause a fire. The circuit must be designed to accommodate the current demands of the appliance(s) operated.

The ignition switch or its wiring is NOT designed for high current loads such that cooling fans can apply. High load circuits such as cooling fans are usually sourced through a fuse rated at slightly above the appliances maximum current requirement, connected to a high current supply (directly to the battery or its main feed), using wiring sized larger than the maximum load the circuit requires and controlled (switched) by a relay rated higher than the maximum current demand of the appliance(s) attached to the circuit. The relay can by triggered (remotely switched) by the ignition switch or any other means as the relay's primary (trigger/switch) side is a very low current draw.

While electric fans can produce energy when they are free spun (windmill effect), seldom does this produce enough current to damage a circuit designed for its intentional load. Any effect caused by windmill would be negated by the switching device controlling such a circuit, as the circuit would be open (off) and would prevent any damage if it did occur (an open circuit applies no load).

Whenever the electric circuit is in demand (on) it applies a load to the circuit and requires horse power to operate it. In our cars the battery/alternator supplies the current required to supply the demand. The battery is the storage, the alternator replenishes the battery. High current demanding circuits will drop the batteries voltage as the demand is applied, the alternator applies the required addition to the circuit to maintain the required load that was designed into the original circuit (complete car). If the alternator can not keep up with the demand the weakest link will fail (usually alternator and battery damage results).

If a new load is attached to a source larger than the overall circuit(s) were originally designed for, the circuit and its sources will need to be redesigned to meet the load (current) demands. This can require a larger alternator, battery and wiring.

And yes, it require horse power from the crank to drive it. The only exception to this is a quarter mile race car that is driven off the battery only during its run down the strip and charged between runs. ONLY then (race situation) can there be a horse power gain to the motor by running electric fans and pumps as there is no connection to the crank.

Again sorry for the book, hope it helps....

Originally Posted by 36 sedan

Sorry for the book on this, seemed necessary.

CFM requires horse power, regardless wether driven by crank or electric (in our cars the electric is driven off the crank). Higher the CFM, higher the horse power required.

Electric fans use current to produce horse power. The more horse power (CFM) the circuit requires, the larger the load (current) demand will be on the circuit. If the load (current demand) is larger than the wire’s capacity or switch’s rating the circuit will fail at its weakest link. If the switch is the weakest link, the switch will burn up. If the wire is the weakest link, the wire will burn up and usually cause a fire. The circuit must be designed to accommodate the current demands of the appliance(s) operated.

The ignition switch or its wiring is NOT designed for high current loads such that cooling fans can apply. High load circuits such as cooling fans are usually sourced through a fuse rated at slightly above the appliances maximum current requirement, connected to a high current supply (directly to the battery or its main feed), using wiring sized larger than the maximum load the circuit requires and controlled (switched) by a relay rated higher than the maximum current demand of the appliance(s) attached to the circuit. The relay can by triggered (remotely switched) by the ignition switch or any other means as the relay's primary (trigger/switch) side is a very low current draw.

While electric fans can produce energy when they are free spun (windmill effect), seldom does this produce enough current to damage a circuit designed for its intentional load. Any effect caused by windmill would be negated by the switching device controlling such a circuit, as the circuit would be open (off) and would prevent any damage if it did occur (an open circuit applies no load).

Whenever the electric circuit is in demand (on) it applies a load to the circuit and requires horse power to operate it. In our cars the battery/alternator supplies the current required to supply the demand. The battery is the storage, the alternator replenishes the battery. High current demanding circuits will drop the batteries voltage as the demand is applied, the alternator applies the required addition to the circuit to maintain the required load that was designed into the original circuit (complete car). If the alternator can not keep up with the demand the weakest link will fail (usually alternator and battery damage results).

If a new load is attached to a source larger than the overall circuit(s) were originally designed for, the circuit and its sources will need to be redesigned to meet the load (current) demands. This can require a larger alternator, battery and wiring.

And yes, it require horse power from the crank to drive it. The only exception to this is a quarter mile race car that is driven off the battery only during its run down the strip and charged between runs. ONLY then (race situation) can there be a horse power gain to the motor by running electric fans and pumps as there is no connection to the crank.

Again sorry for the book, hope it helps....

Amen!! Your description is thorough and accurate in all respects, IMO.

Originally Posted by jerry clayton

running his fan load thru ignition switch on terminal lets the rotataing fan create a reverse charge circuit that fires the ignition

While this can happen when the car is stopped in extremely rare cases, the current produced by the fan rotation depletes rapidly when there is no power source (wind or other) to continue their rotation. And as this generating effects current is applied to the coil to run the car slows down so does the firing of the coil bringing it to a stop (usually quickly). Further, the load applied to the fans by the coil's demand acts as a brake to the fans as the load applied across a generator requires horse power thus lessoning their rotational speed faster.

Afterrun is usually caused by a hot spot in the cylinder, be it carbon or metal surfaces themselves, the heated area fires the fuel charge as it enters the cylinder causing a very rough and uneven continuation of the motor. It is a sign of other problems that need to be addressed and corrected.

And agreed, the guy needs to fix his electrical system as well.

Can after running or a motor deiseling after shut off cause a head gasket to blow?

Originally Posted by 84Camaro

Can after running or a motor deiseling after shut off cause a head gasket to blow?

Remember from school, i before e except after c.....dieseling

I would think that it could, because dieseling is detonation and detonation can cause a blown head gasket. It's like a sledgehammer blow to the crown of the piston too, so could crack pistons and rings or at least smash the top ring land and pinch the rings so that the motor has insufficient compression to operate properly.

.