Author Topic: M42 overheating (Read 4222 times)

willworkfore30s · « **on:** April 16, 2012, 01:07:09 PM »

Motor is stock other than my mess under the intake mod.

I capped the port on the block and the top of the coolant tube.

Radiator is not original and appears to be in good shape.

Coolant level is good.

It doesn't heat up particularly fast but keeps heating up past normal. I haven't let it get much past the 3/4 mark.

Drove it 7 miles to school today and pulled into wendys and sat in a long line. It started running up past half and got to about 3/4. Turned the heater on full blast and it kept it at bay and slowly started cooling back down.

Drove it a mile further to school. Got out and checked the passenger side coolant hose and it was hot. Making me think the thermostat is working properly. But I am not positive about that.

Today is not the first time it has done this, its just characteristic of how it does for diagnosis purposes.

My next step is to remove the thermostat and see what happens.

Any ideas, suggestions?

willworkfore30s · « **Reply #1 on:** April 17, 2012, 12:17:39 AM »

So I drove the car about 10 miles tonight to the movies. Stopped to let my friend run in somewhere quickly. Went to turn around in the parking lot and my check engine light went on and the needle on the temp gauge went from less than half way up to pegged very quickly.

I turned the car off. Got out and slowly unscrewed the radiator cap. Nothing abnormal, no boiling over. Motor didn't feel excessively hot. I could lay my hand on the intake and valve cover without burning myself.

Get back in the car, go to crank it and get nothing. Not a click click of the starter... nothing. Give it a minute, try again...nothing.

Push the car down a sloped alley, jump in, slam it in gear and dump the clutch. Car cranks. Temp gauge shows just above quarter mark and the car runs like normal.

Does it have a safety feature that was activated by the ecu because the car thought it was overheating?

willworkfore30s · « **Reply #2 on:** April 17, 2012, 06:17:02 PM »

Kinda surprised by the lack of response to this thread but just in case anyone else has these problems i figure I'd keep updating for their benefit. Any advice of suggestions are still very welcome.

So after last nights escapade I decided to try and drive the car to school since I was pretty sure now that my over heating issues were really just a messed up gauge wire. I get on the high way and immediately hit traffic. After a while gauge pegs. Even though i know that is pretty much meaning less, seeing that made me nervous.

So I finally make it through traffic, already late for class and the car starts bogging down and I can't get power. I limp off the high way and pull over. Check the radiator. Coolant looks normal, can remove the cap with out it spewing over and its not boiling when I look in. So it didn't over heat.

I am gonna be late so I decide to see what it can do. Crank it up, runs a little rough but has power. I drive it back home to swap it out for my truck. It makes it fine. Gauge shows 1/4 mark on temp all the way home.

Get home and check it. Area on the "frame rail" where the gas lines attach is wet. This area also caught fire briefly a few days ago while I was tack welding a strut brace. The fact that it is wet now and caught fire so easily then leads me to believe my fuel lines are leaking and that could be what has been causing my stumbling issues this whole time.

I will replace the lines some time soon and report back on if that fixes my issues. I will also see if I can repair the coolant gauge wire and see if I can sort out the "overheating" deal.

keflaman · « **Reply #3 on:** April 17, 2012, 08:21:16 PM »

Here's a thread I wrote up a few years ago explaining what I found when my temp gauge was acting wacky and what I did to correct it. I'm fortunate in that I own an old Snap-On "Brick" and read my temp directly from the ECU and can confirm that my gauge reads correctly.

http://m42club.com/forums/showthread.php?t=7718

b_cyrus · « **Reply #4 on:** April 18, 2012, 03:13:18 AM »

interesting. I was having this issue on the freeway, but I figured it was just because of the car having it's clutch fan removed.

rob_e30 · « **Reply #5 on:** April 18, 2012, 08:20:24 AM »

I suspect a bad fan clutch. Area where it was wet could also be the expansion tank venting. Don't be too quick to discount the gauges.

doitover · « **Reply #6 on:** April 18, 2012, 02:01:02 PM »

If the water pump wasn't pumping or if the thermostat was not opening the engine would overheat without the radiator becoming hot. If you were at running temperature and able to remove the radiator cap without blowing steam all over, something would be wrong, wouldn't it?