Hi all, I don't come on here very often, but I've been a member since I got my 1996 850 GLT wagon over 4 years ago. I try to take good care of it--change my own oil (synthetic blend), use the good gas (93 octane), take it in for regular inspections and fluid changes, filters, etc. "The Brick" (creative name, huh?) has never given me much trouble...until now.

Coolant started leaking from the top of the radiator, where the upper hose goes in, about 2 months ago. I couldn't afford a new radiator yet so I just kept adding fluid to it as it leaked out. Then, two weeks ago, idling in park at a drive-thru window, the radiator shot out a huge amount of coolant and steam. At the same time, the temp gauge bottomed out and the engine, which usually idles around 900 RPM, shot up to over 3000 RPM although I hadn't touched the gas. I put the car in gear to limp it into a nearby parking space and the engine almost died when I did this, then shot back up to high RPMs. I parked the car, shut it off, and let it cool for about 40 minutes. Then I added coolant and tried to restart the car--it would crank but wouldn't start.

I came back 36 hours later and the car just started right up like nothing happened. All gauges normal. Computer diagonostic revealed nothing, no related/applicable trouble codes. Radiator was cracked; I scrounged up the money and had it replaced. My mechanic "drove the hell out of it" afterwards and no problems.

Over the next few days, intermittently, the temp gauge would bottom out and the engine speed would increase while I was driving--just a slight increase in the RPMs and a tendency for the engine to keep pulling when I let off the accellerator. I theorized that the engine coolant temperature (ECT) sensor was shorting out--the only thing I could think of that would explain both the gauge falling and the engine speeding up (choke, because the computer thinks the engine is cold and so sends richer mix to the engine). I ordered the sensor, it will be here tomorrow morning.

Today, the car did it again while I was driving, but the engine shot up to very high RPMs like the first time, and the engine began running rough and shaky. I pulled over and parked (just a block from work). Sure enough, a few moments later, the engine would crank, but not start. I spent 7 hours at work and came back. It started, but just barely. The poor thing sounded like it was trying to run on 3 cylinders. So I had it towed back home.

I can understand a bad coolant temp sensor being responsible for a small increase in RPMs (choke). But 3000 RPM at idle? Or sounding like it's shaking itself to pieces? That sounds more like a TP sensor (which is very expensive). What are the chances that both these sensors would go out at the same time? I am going to test the thermostat tomorrow morning when I put in the new ECT sensor on the chance that the poor thing has been overheating and couldn't tell me. If that's the case, the damage has been done.

Any ideas as to what is happening here? What else should I check? Anything I do is going to have to be DIY and cheap, because I already owe several friends that spotted me money for the radiator. Eep!

Check the wires on the ECT sensor and make sure they are not frazzled or cracked, which could cause the intermittent temp reading. Some coolant on the wire could also short it out.

You need to look for either a vacuum leak, large, or a very dirty throttle body that is causing the high idle. Remove the cover over the throttle and look at the large hose from the idle control motor. Then inspect the vacuum tree, make sure it is not loose and no extra holes in it.

The ECT sensor will not change the idle very much, but will make a warm engine run poorly.
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My name is Klaus and I am a V♂lv♂holic

Thank you, KlausC! Every time I've had a question here, you've been among the first to answer it. Today I replaced the ECT sensor and the thermostat, just for good measure. I located my vacuum tree and checked all the lines. All seemed to be secure except the large one coming from the top of the tree. It was loose and had no clamp on it (in fact looked like it never had had one), so I installed one. I didn't tighten it too tight because the fitting is plastic, but it's secure. I also removed the cover between the camshafts (where the spark plugs are). There was a lot of oil pooled in there; the clamp of the small hose in the center was very loose so I tightened that and mopped up the oil. I drove some short trips and it seems to be doing well, though since the problem has been intermittent I am not totally convinced that I'm done.

I feel like an idiot because I cannot seem to locate my PCV valve. All the pictures in my Chilton's manual are for engines other than mine; mine is a B5254T. Also the throttle pulley cover is missing on my car, has been since I bought it. Chilton's says "remove the hose from the nipple on the intake manifold." Which hose? Which nipple? I know where my fuel rail is; is that what they mean? It's just hard with no pictures.

LOL, If you have a low pressure turbo, there is no PCV valve.

The loose hose on top of the vacuum tree is the culprit to the high revs, that is the connector to the idle control motor which is supposed to give just enough air to keep the engine at proper idle.

The hose on top of the cam cover is there to catch fumes from the cam area and direct it to the oil separator (under the intake manifold). You done good with a light clamping. Some of the oil up there can be attributed to a hard rubber seal on the oil cap and people who spill a 'little' oil when adding a few quarts.

Sounds like you are good to go for a while. Pay back your buddies!!

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My name is Klaus and I am a V♂lv♂holic

According to Chilton's (I'm gonna get the Haynes), the "T" at the end of my engine code is not for "turbo," it's the year code for 1996. It's a normally-aspirated 2.4L engine. I wonder if someone beat me to the punch long ago in removing the PCV filter screen. I undid all the air cleaner hoses, both ends, and every hose in the intake area that wasn't obviously a vacuum line or a fuel line, and found no screen and no dirt (although there was a little oil in the bottom of the air intake on the engine end of the hose, which I mopped up).

*shrug* Sunday, I'm taking it over to my mechanic buddy's house and we're giving it a thorough going-over. Something inside the front passenger-side tire rim is spitting out copious amounts of thick, silvery grease. CV boot is intact, and in fact we just replaced the half-shaft on that side a couple months ago.

Thank you for the praise, KlausC! I feel vindicated in using a little common sense, even when I don't totally understand the manual. Thank you for showing me what areas to pay attention to.