Maybe but at same time a serious backfire through intake can kill a engine and damage injectors (and some sensors) and sometimes carbs. Again I am not rulling out you idea it is just I have seen some real serious back fires in my life and some that caused damage to point engine would not run until it was repaired.
TheSnoMan.com
Mike and SnoMan, The jeep runs ok now. Here's what the mechanic found (after a couple hundred dollars worth of diagnosis): He believes when I hooked up the Brake Booster (mentioned in another post) which by the way leaks, this caused a lean condition on the engine and caused it to backfire. However he says there are hydrocarbons in the cooling system, which leads him to believe one of my heads is cracked. He asked if I wanted to replace the heads, I told him no thanks, if the Jeep runs, that's fine by me. So now it runs fine.
Gents, thanks for all your assistance. I'll just drive the Jeep for now. The heads will have to wait until I get some cash.
Thanks for the update.
I would just keep a close eye on the rad fluid to be sure it isn't leaking into the engine.
I know lots of folks that use a bit of oil on the rad or heater hoses to help them slip on. This will give a reading on a tester. So will using an oil dirty funnel for coolant.
Mike
Anth> Mike and SnoMan,
Mike, the one thing I forgot to mention is anti-freeze does come out the overflow cap tube when the engine has been running. The mechanic says it's caused by the cracked head pressurizing my cooling system (he believes). I'm not so sure. He added a bunch of anti-freeze to the radiator so I'm wondering if the cooling system is trying to equalize, or find equilibrium. Having said that, my temp gauge rarely goes beyond 1/3 (it never reaches half-way) and it's been like that for years. thoughts.
The newer rad systems are designed to use an overflow bottle and have the rad full to the top all the time.
This means as they warm up, the coolant comes out of the rad into the overflow bottle. The rad cap is a two way cap. As the rad cools down, the coolant sucks back into it.
I currently have no overflow bottle on my CJ7 so I can only have the coolant just covering the cores by 1/4" or so or it will puke out on the ground.
The older rads with the side tanks and horizontal cores were better for the open systems. You could just have the fluid down a ways on the side tank and still not worry about dry cores.
One thing I do when checking out systems is to warm it up with the cap off. If there is exhaust pressurizing it, you can usually see smoke coming out the rad cap.
Mike
Anth> Mike,
Thanks again, I'll check it with the cap off. stay tuned.
Yess this is what it was designed to do
This makes no sense at all. With a horizonal core with side tanks and the level drops in tanks, more of the core is exposed. A vertical core with a tank on the top can be run a little low on coolant and still make use of the complete core. This style also better tolerates having no recovery tank but it is kinda foolish not to use one because it allows the air to burp out of system to prevent cavitation of pump. More than anything hood lines and stylingm mandated a design shift from vertical to horizonal cores and coolant recovers tanks allow for the horizonal cores to be kept full all the time for best efficency.
Sometimes it can just be steam too so this is not a good test unless it is a real big leak. As stated earlier a long term pressure test with air would reveal if there is a leak. You want engine temp at ambient temp because if you start with a warm engine that cools the air contracts as it cools and can cuase pressure to drop some and change readings. Water expandes to when heated and the reason you have a coolant recovery system on most newer vehicles.
----------------- TheSnoMan.com
The design engineers thought it made sense. If you have 4" of a side tank open to air, then 20" or more of cores are still fully filled with fluid.
The side tanks had a 'full hot and full cold' mark on them even.
If you are down 4" on a top tank 'all' the core tops are open to air and only the ones at the very edge below the top rad hose will run coolant when the pump flows, the rest are air locked with stagnated coolant.
Emissions mandated the closed systems, not hood designs.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
No you do because the engineers came up with the coolant recovery system to better deal with this problem.
THey did noi mandate horizonal cores, lower hood lines did that because it allows longer core time for coolant than a shorter path in a vertical core.
TheSnoMan.com
I've got to join in with SnoMan on this one... and as a cooling system design engineer I can vouch for his statements.
With a cross-flow radiator you get more core face area under a low hood line. You also have fewer tubes (within some limits) which means lower cost to produce.
Down flow radiators do operate at near full capacity even if the top few inches of the tubes 'run dry' - they don't really run dry because the coolant in the top tank still passes through these tubes in normal operation and dissipate heat the passing airstream.
On a cross flow otoh, when the tubes are dry they really are dry since the coolant in the side mounted tank falls to the bottom of the tank before it enters a tube.
Car makers run a test call 'pull down' to ascertain how much coolant can be lost and still maintain effective cooling. Down flow radiators have a greater margin than cross flow.
And a coolant recovery system with a good cap is the best way to ensure effective cooling. Replacing the cap every year when you change your coolant is a good idea too.
reboot
I used a Corvette four core cross flow in my CJ-2A because of size restrictions, you mentioned. We disagree BIG time on running it low, the coolant doesn't back up enough even at high RPM to use any channels above the level. Making the pressure cap and recover tank, you mentioned critical! Probably the biggest reason we don't see any Renaults on the road. God Bless America, Bill 0|||||||0 mailto: snipped-for-privacy@aol.com
What 'are' you fools going on about?
The horizontal cores with side tanks that I said are better for an open system is the 'old' way of doing things in a Jeep CJ because you always have some cores full of coolant.
The new CJ and TJ rads have top tanks with vertical cores and don't work as open systems due to the reasons I gave above that 'all' the core tops get air locked when low on coolant.
Snoman likes to take words out of place and reply to seeming nonsense.
Look at the 'header' of this thread 'very carefully'. On my PC it says CJ-5 and pointedly mentions a 350.
I will repeat. Closed systems came into being because of pollution concerns about the coolant puking out on the ground. PCV systems also came into being because of pollution controls as the downpipes were leaking lots of oil onto the road also. Charcoal canisters or gas tank vapor recovery systems also came into being so fumes didn't pollute.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.