308 Cooling Issues

Sean get the new thermostat. I have a 77 without the bleeder on the thermostat and have no problems bleeding the system when I do my annual fluid change. Every 3 or 4 rides I cold bleed my rad. and have no problems. It is strange that you are not moving hot coolant up to the rad. That is what makes me suspect there is a problem of closing off the port and pushing water to the front of the car. Just as a point , I have never needed to stick a screwdriver under the hose at the thermostat to bleed out any air. I replaced my waterpump a few back and never had any bleed issues. Keep going and don't give up and you'll get it. Also I assume that the timing is OK and the dizzy's are working correctly. And you may want to check the coolant for exhaust gasses. Last put on a new pressure cap and make sure it is sealed. I use a 13# stant cap but you can go to the 16# one if you want to. I believe the part number is in the 308 parts thread at the top of the 308 form. Good luck.

 

RADIATOR EXPANSION TANK CAPS
STANT 11229, 13PSI, FITS TIGHT
ALSO STANT 11230

 

DUDE!!! Thats freaking scary looking. Did that metal corrode off and into the coolant system? It might be worth getting your coolant system flushed at this point to make sure no more "gunk" is anywhere PLUS if any metal did detach, get it washed out.

That scares me for my car............

James in Denver

 

It's replaceable but it might be next to impossible to do in the car. You might have enough room but you will probably need to drill it out and retap the housing. If the hose and that fitting look that bad you might just want to pull the pump and rebuild/replace it anyway.

 

Welcome to the world of "workin thru the wheel well". I would suggest that you start the process now of pulling out the complete waterpump assembly. Start looking under search fo the waterpump removal. Based on what I see in this picture it looks like someone was in there already to replace the WP and the other fittings. I am suspect to what the orange stuff is around each fitting. I don't believe this is OEM material. Also you should check with the previous owner if they knew when this work was done. The condition of these parts are terrible. It's been a long time since I saw this type of corrosion. It makes me wonder if there was a cooling system corrosive flush that was done. Maybe others can chime in here but this does not look normal. Also with the brown stuff maybe someone put in some "leak sealer" stuff because of othere problems or maybe this is the remains of the chemical flush. Guess you gota rebuild/replace the waterpump. Good luck

 

Sean,

If you are throwing the thermostat into boiling water, you are not testing it properly. You need to suspend the thermostat in a pot of cold water, and use a thermometer in the water (not touching the bottom or sides of the pan) to track the temp of the water as you heat it up. Check the rating on the thermostat. Probably 80 deg. C, or 82 deg. C. The thermostat should be opening at that temperature, NOT at 220 deg. F. (100*C). If it isn't opening until 220*F/100*C, it's not working right. If you are simply putting the stat into a pot, and it is sitting on the bottom, you are not testing it properly and it could actually be opening way over boiling point.

If I were you (and I did this over the winter this year), I would remove the lower hoses in the front, drain the system, disconnect the hoses from both sides of the engine, and blow them clear with fresh water from a hose. That will let you know whether either of them is clogged. If both are clear and water runs free, then try flushing the block. If the block won't flush, you've got a clog somewhere and have to trace it down. If the block flushes fine, then close the system up, raise the rear end a little bit, open the heater valve, open the bleed valve on the radiator and on the thermostat housing, and start pouring your mixture in through the expansion tank. You should hear the air coming out of the bleed valves, both front and rear. Coolant should come out of the radiator bleed valve before it comes out through the thermostat. If it is coming out of the thermostat but not out of the radiator bleeder, there is something wrong. When it comes out of the radiator, close that valve, and keep adding unit it comes out of the thermostat housing. Close the thermostat bleeder, fill the reservoir half full (NOT 1" below the neck), start the engine and see what happens.

Now, separately, you may have a problem with the fan switch or fan circuit. Be sure to check that was well. If the radiator is getting hot and the fans are not coming on, you need to check the switch. You can always bypass the switch and have the fans on all the time until you can get a new switch, if necessary. If you have the car on and jump the switch and the fans don't come on, trace the circuit to be sure you've got power, that a fuse hasn't blown, or that a relay is not working.

BTW, if you haven't heard about it already, check out the Birdman replacement for the fuse blocks on the 308. You can install them in about 1/2 hour, including changing the fuses. You should also buy all new relays (you can get them from rockauto.com) and replace them as well.


Hope that helps.

 

Ouch, did not see your last posting before writing. That brown gel crap is probably 10 year old coolant and rust. If I were you, I would definitely drain the whole system after you've driven the car for a few days, and flush everything out. Pay particular attention to the radiator, as any crap circulating in the system can end up stuck in the radiator.

Enjoy driving the car. I just had mine out for a ride tonight, took my son out and he was loving it. They were made to be driven, so now go drive it like you stole it.

 

take the expansion tank to any radiator shop and they can braze a new fitting in. seems you could drill and tap the thermo housing for a drain plug.

 

My water pump nipples looked just like that. They totally disintegrated when I tried to remove them. They are replaceable. My recollection is that the big one is about $80 and the little one is about $45 from the usual suspects. I had to buy a tap for the small hole because it was corroded so badly that the replacement didn't go in well and the threads needed cleaning. They are not pipe threads but straight machine threads so they should have some sealant on the threads.

Oh, and there is another nipple on the other side of the engine, poking out of the rear head. On my car it looked good, but someone else here had the same corrosion on that nipple as well.

 

I did not have an overheating problem but I did have a random fast idle. I will say that the coolant nipples on my car did not look anything like yours (much less corrosion on mine). It looks like the same coolant was in your car for WAY too long and the pH balance went way off because of it.

By the way, I bought a digital pH tester a couple of years ago and it comes in handy for checking many things including coolant. It was not cheap but can save big $$. I've found that the cheap paper pH test strips are pretty useless. Not super accurate and they leave too much room for interpretation by the user.


My recent post:


"Okay Luigi.... I know your car is rather different now but I had a similar problem with my 328. The fast idle seemed kind of random. I mean the engine could be fully warmed up, I shut it off for only a minute or two and when I restart I get high idle again (around 1500 rpm). Would also happen at a stop light when I take it out of gear etc. I verified that the aux. air valve worked properly when heated and cooled and I did not find any vacuum leaks on the engine.

Recently I removed the coolant bridge (in the photo) that connects the two coolant manifolds from the heads. I found that the small pipe, on the bridge, that runs to the coolant expansion tank was plugged up with "gunk." I would say it was at least 50% blocked. The rest of the cooling system looked very clean. For some reason, probably the small tube diameter, it likes to collect in there.

Anyway, this tube allows coolant to circulate through the expansion tank. The coolant continually goes in and out of the tank and this means the coolant temperature in the tank should be more or less representative of the coolant temperature in the block. This is important because the aux. air valve is mounted to the bottom of the coolant tank and the water temperature in the tank dictates how much the air valve closes (reducing idle). Now.... if the small tube going to the expansion tank is not passing as much water as when it was new (because of the blockage) the average temperature in the expansion tank will probably be lower (colder) than it should be in comparison the majority of the coolant in the block. If the tank temperature is abnormally low because of poor circulation the aux. air valve will be open to a greater degree, resulting in a higher idle, because it "thinks" the engine is cold (or colder than it really is).

Unfortunately I cannot verifty that cleaning this coolant bridge tube on my car solved the problem because I have removed the aux. air valve, vacuum valve, cold start injector etc. from my car along with other parts. I'm hoping these parts are not essential but I will not know until I finish the major + on my car and see how it starts/runs.

Also, I know there are some variations between models. I don't have a temp. switch on my coolant tank, a lambda sensor, frequency valve etc.

Erich"

 

I'm curious about the idle on your car (because of my theory). Did it seem to be too high or high too often (when the engine was at full temperature)? Did you make any adjustments to it/compensation?

 

I keep coming back and looking at these pics, and while I dont want to sound an alarm, I bet this engine would be next to impossible to gets the heads off.

 

Yep I have to agree, that gunk in theory will be everywhere.
I would be quite worried also.
I reckon you need to give the whole coolant system a good look over.
That includes the aluminium tubes that run fore to aft and every other bit.
Beware!
Just think what the internals of the engine could be like.
For those that think leaving the car to sit around for ages without really running it is a good thing and that having a car that is 30 years old but only done 5000 miles on the clock is a good thing, think again.
A barn find is maybe just that. Something that should stay in the barn.

 

Most quick oil change places have a coolant flush service available, that might be something to consider in this case. I'd have them drain what they can first,(get the big crud out) then flush the system.

 

I agree with Paul, getting the heads off would be interesting, I am working on a 308 QV that is a horror show at this time with corrosion due to the cooling system, it’s time to switch to EVANS NPG coolant, I have been running it in my cars for a few years now, no pressure, protects from boil over, eliminates system scaling, reduces corrosion, eliminates pump cavitation, permits more spark without detonation, prolongs hose life, coolant will last the life of the engine, it is rated at 500,000 miles, a must for Aluminum engines! It is also essentially non-toxic. $32.50 per gallon, worth every penny when you look at the potential long-term damage that can be caused by water & antifreeze to an aluminum engine, also keep in mind that a water-based coolant is operated near its boiling point. Cylinder liner cavitation erosion is caused by vibration-induced high frequency pressure changes at the metal-coolant interface. Coolant, near its boiling point, makes vapor bubbles that abruptly collapse against the metal surface, causing erosion of the metal. EVANS NPG Coolant contains no water and is not operated near its boiling point.

The boiling point of EVANS (non-aqueous propylene glycol) NPG Coolant is 370 degrees F in a non- or low-pressurized system. The coolant is normally controlled at conventional temperatures but functions perfectly well at higher temperatures, even considerably higher temperatures. Detonation/pre-ignition control and previously forbidden combustion chamber pressures and temperatures are no longer the danger they were to thermal engine efficiency and durability.