Bonneville America Forums Forums Technical Forums General Tech I know, Im sorry, but need help...

I know this isn't a automotive forum, but I have tried to register at "Maverick.com", and it ain't happening. I know there's an immense amount of knowlege here on this site, not only for our bikes, but for very simple internal combustion engine problems, like Im having. My son's 1974 Ford Maverick, with the 200 "6 cylinder" is kicking my butt. The waterpump went out on it, simple enough, right? NOPE...Not for me...I've been hexxed by this car since I've got it for him. I removed the water pump, figured I would change the thermostat while Im at it (big mistake), and snapped one of the bolts holding the thermostat housing to the engine, but was fortunate enough to have enough of the studd sticking out that a torch and vice grips got that out. Replaced thermostat AND water pump, reinstalled radiator and fan after pressure washing the inside of the engine to flush her out real good (2500 psi). Started her up, and suddenly a strange "gurgling/knocking" sound starts, and steam everywhere. I look inside, and the oil light is flickering, with a slight pinging coming from the engine. I realize the head has been warped, or head gasket blown, somehow, as there appears to be water in the oil. I changed the oil out, new filter and did compression check..all cylinders are 120-150, so thats good news. She runs good for 5 to 6 minutes, oil light now out and not flickering anymore,then all hello breaks loose. Spraying antifreeze and steam everywhere, like the radiator is being super pressurized. I know the thermostat went in the same direction it came out, and I can't understand why its pressurizing and overheating so much after running for such a short time. Radiator definitely leaking (no idea why, it was'nt leaking before I started), so it's off to the radiator shop this morning. How can such a simple engine be so difficult? Maybe Im missing something here..any ideas would be appreciated...

I had a Plymouth engine that punched through a gasket (don't remember which one) and allowed pressure from firing cylinders into the cooling system, over-pressurizing it and blowing coolant past the thermostat housing gasket. (Not to mention blowing holes in the aluminum radiator.) I'd think a perforated gasket would show up in your compression checks though.

I ended up with a new engine because the metal where the gasket used to be was eroded by combustion products.

Dave

I've heard of thermostats being faulty and not opening brand new out of the package. Maybe take it out and run the motor without to see if it still happens.

I'd agree with Dave,thats the first thing I would do.

Mark, is it possible the thermostat went in backwards?

Try running it without the thermostat, as it is running look inside the radiator (with the cap removed) see if there is any bubbles coming up though the water (coolant) you can also check the thermostat by putting it in a pan and put it on the stove. You can throw in a nice little 302 if the straight six is junk!!!

Sure sounds like a head gasket to me. I see 2 possible problems. 1) If you heated the head where the thermostat goes in with the rest of the head cold you may have warped it depending how hot you got it. ( I think the thermostat went in a recess in the front top of the head on those if I remember right.) 2) the pressure washer damaged the head gasket allowing pressure into the water jacket and oil into the water. If you pull the head be sure to take it to a shop and have it check to be sure it's flat. I have a special straight edge I bought for doing that. That is used with feeler gauges to determine the amount of warpage. In most cases the head can be planed flat again.

When you filled the cooling system up did you run it with out the cap on and did you top it off once you see the t-stat opened ? if you just filled it up and put the rad cap on it will be low on coolant when the t-stat did open causing you to have air in the system and building up temmedous presure , just as you described . remember the spring on the t-stat sits in the block .

Cylinder compression is 120 to 150. That's not good. Quite a range there. I agree with Ian and Dave's assessment regarding a blown head gasket. You didn't state if the engine had been overheated previously. With a leaking rad, water pump etc, it probably did. A small pinhole in the head gasket will pressurize the cooling system and show up as lower compression. The gasket probably failed in more than one area allowing coolant to travel to an oil drain gallery. Not sure if you were actually able to pressurize the internals of the block to 2500 psi as stated while you were washing the guts but if you got it anywhere over max rating (guessing 50 psi), your gaskets including the intake wouldn't have been able to handle it. That's the only way for coolant to get into the oil (unless something cracked). Is there coolant back in the oil now?

But the key to the compression test is did it hold at those numbers , if did hold then the head and gasket are fine I mean we are talking about a very anemic 7 to 1 c,r, 70s six cylinder here

The car ran fine up to this point, the reason I changed the water pump is due to the fan hitting and loose at the water pump...Radiator leaking profusely, took to the shop this morning, can't be saved...will get another radiator and go from there...changed oil, runs fine for 5 minutes or so, then starts spraying, seems to be superpressurizing.......Thermostat went in the same way it came out...Engine runs really good until she starts spraying from the radiator and getting really hot.....old oil did'nt appear to have water in it...just really thin.

You're probably getting a combustion leak into the cooling system, causing the pressure to increase greatly. Could be anything from a head gasket to a cracked head/block.

Check it, or get it checked with one of these: Block check

If it's positive, you need to pull the head (pretty easy on one of those) and get it checked for cracks. Then take it from there.

If it's negative then you most likely aren't circulating coolant correctly; bad/wrong stat, bad/wrong pump, incorrect fill procedure, or more.

Hot oil will be thin. Water will turn it milky.

The only reason I think it is more than just a bad stat or circulation problem is the water in the oil. A bad stat won't do that. I also discounted the cracked block since it was fine until the water pump change and pressure wash. Was the engine run enough to get hot before filling with coolant? Or was it filled with coolant while still hot from the torch? Those 2 actions could crack the head or block. A crack would cause those problems too.

Removed thermostat housing, Thermostat installed backwards. Reinstalled thermostat, awaiting radiator from e-bay...I think she's gonna be alright...

There is a couple clues in your horror story that indicate head problems either gasket, warped or cracked head 1. water in the oil (milky white) and high pressure getting to the cooling system. The thermostat allows heated water at the thermostats set point to go through the radiator. If it hasn't reached that temp the thermostat will not open. It will take about 5-6 min to get to that temp, so at the most your thermostat is probably just starting to open.
Now i am testing my memory, but I believe there is no overflow system on the 74 and the radiator cap may be venting the extra pressure/coolant out of the vent line on the cap.
If you have a pressure tester you can check by placing it on the radiator instead of the cap and start the car if pressure runs up quickly it is defiantly something with the head. (best done with 2 people incase you need to turn the ignition switch to off quickly.

What do you mean by installed backwards? If you mean installed upside down with the sensor end pointing up out of the block that is a problem. Was it upside down or rightside up. Orientation of the thermo when it is installed upright shouldn't really cause what you are experiencing.

Some questions that need to be answered before you continue.
1. Is the oil contaminated with coolant now? If so big problem.
2. Have you properly filled the system, warming the engine with the cap off until the level dropped (thermo opened) then continued to fill up? Already posted.
3. Have you checked for compression gasses in the cooling system as already mentioned on several posts? (rapid pressurization, pressurizing the system so that the cap relief blows, coolant test devices, etc.

It's frustrating trying to help from a distance.

Also if you are getting combustion gases in the cooling system you will destroy the new radiator in very short order so you should verify what your problem is before installing that and trying to run the car.

Radiator arrived, perfect match, no leaks, but engine won't start, no fire at the plugs....Have fire at points, but not at plugs. Replaced ignition coil, engine running better than ever. My son drove it to school this morning....fact that thermostat installed incorrectly, coupled with pressure washing inside engine was the problem....Nothing quite like the sound of an old 6 cylinder going up the road...Lesson learned.

Glad you got it fixed,if the thermostat was the problem then you weren't getting exhaust gases in the cooling system or coolant in the oil unless you have a weak spot in the head gasket that the extra pressure allowed coolant to get past. I would keep an eye on the oil for a while until you are sure.

I am sure your son is happy having a car. Second keeping an eye on it. That would be great if all it was was the radiator.