I have been reading the forums for a while. I thought I would have plenty of time to do an intro sometime but I think it is time for the old dependable Dakota to start needing work and now I am in serious trouble. I spent an hour searching the forums to make sure this wasn't a duplicate and was already answered.

A few months ago my wife called and said the the temp light came on so she pulled over and shut it down and let it cool and it started and ran fine. When she got home I took it for a drive and all was good. Maybe three months and 3000 miles I had a check engine light on cold start with a ton of vapor out of the exhaust that smelled like emissions and not coolant that would go away shortly after takeoff. A couple of days later when I did a cold start on concrete and let it idle it was pure water coming out of the exhaust like emissions. The code showed misfire #6. I figured with 125,0000 miles it needed plugs. A few days later it started running hot and the top hose was hot and swelled and bottom cool so I figure thermostat. While replacing the thermostat (breaking the bottom housing bolt off which will be another repair) I needed to back it up a couple of feet so cranked it with no coolant no thermostat with the radiator hose off and immediately got tapping noise from the top rear of the engine . Thinking I had something in the fan or it didn't like no coolant I shut it right back off and replaced the thermostat and plugs. All the plugs were worn out but looked good on color except (#6 ? right rear of engine viewed from drivers seat ) which was black and wet looking like oil/fuel. Test driving, thermostat will not open, has a dead miss, bad tick like metal on metal at the top rear of the motor. If it was in the bottom I would call it a rod knock.

I am thinking that something is pressurizing the coolant holding the thermostat closed (head gasket, crack etc from running hot?) bad new thermostat ,and/or a rocker problem and that when I cranked it with no coolant pressure on the engine the rocker cut loose.

With a miss the compression test wont be accurate so I am thinking first step is pull the cam covers (have not looked at manual yet) and figure out what the noise is to fix that to be able to get an accurate compression test.

With each event leading to another I am getting concerned it is major.

Any help and opinions will be appreciated as this is a life changing event for me because I only have one vehicle to commute in and it is still not paid for and I am doing this on limited funds.

Thanks,
Robert

 

You got a dead coil on #6 cyl , it`s easily replaced , could it`s not working cause the tapping noise you hear ,, maybe ?? Your engine could have a bad water pump that`s not circulating the coolant or a stopped up radiator not allowing sufficient coolant flow through it contributing to the overheating problem ,, I would try a new coil first and since you ran the engine with the misfire on #6 you`ll need to pull that plug out also and either clean it or replace it again before you install the new coil on it .

 

Will check those out. Thanks. After stepping back its looking a bit better.

 

After replacing the plugs and clearing codes it never set again but I went ahead and swapped the coils to see if the noise would change but it didn't. It is a definite tap that sounds like it is coming from under the intake towards the rear.
I can feel it there. It taps light continuously and then hits hard occasionally. CAM hitting a pushrod? If I don't hear any better ideas will pull the right valve cover and see what I can see.

 

The 3.7 overhead cam engine doesn't use pushrods or rocker arms , it`s probably a collapsed lifter assembly making the noise , i could be wrong on that , but , if you pull the valve cover off and dont see anything obviously wrong - then that would be my best guess at it . I have never tore that far into a 3.7 motor but i do have some experience working on them , my wife drives a `02 jeep liberty 4wd with the 3.7 engine and it has over 165,000 miles on it now , had 98,000 on it when she got it !!

 

The pics from the 4.7 tear down link at the top of the forums (sticky) look just like the 3.7. Will see.

 

I see what you mean , cam follower assembly`s - who`d a thunk it ? I missed that when i looked up the engine parts on rock auto trying to get an idea of what was involved under the valve cover , and that`s when i thought the cam just rode on the lifters like on some ohc 4 cyl engines . Sorry for the confusion , going back to my corner now

 

The cams are out in the pictures. They are on top of the valves. You can see the empty mounts. (i think) I have read in the forums about them having the rocker arms come off but never read about the noise.

 

Pulled the right cover and the rocker off #6 fell out. Rotated until I could get back under cam put it back together and test drove it. With the new plugs ran like a champ. A couple of colds starts working on the thermostat must have fouled the plug which was slam worn out, missed and threw the rocker arm. Half of the plug electrodes were gone and maybe a bit more on #6 and they had worn down to a .60 gap.

Now back to the original overheating problem.

 

Was busy working trying to make up the money I lost being on vacation.
The short of the story was coincidence. Overheating turned out to be the thermostat. If I had gotten the plugs in on time it would have been routine. But when your motor blows up because you cranked it with no coolant you really have to start wondering. Only thing left is the bottom thermostat housing bolt. I should have checked the thermostat brand because I bet someone replaced it and overtightened that bottom bolt. I snugged the top and clamped the bottom with a pair of vice grips for now. Essentially done but will tackle that broken bolt when I put the hoses on because it is almost impossible to drill without pulling the fan shrouds. Now that I know how to strip it down I would have stopped when the bolt got tight and pulled the shrouds then.