Can engine blow out while temperature gauge shows normal?
 

My Volvo V40 (2000) failed inspection because the Check Engine light was on. The station said to get it to pass inspection we needed: a thermostat & gasket, a catalytic converter, and an engine coolant temperature switch.

We continued to drive it with the rejection sticker, since it drove fine. However, a week later it overheated, right at a gas station, and I pulled in hoping I just needed anti-freeze. But the radiator was leaking, so they replaced the radiator and also changed the oil twice, hoping that this might make the Check Engine light go off. My wife picked up the car and drove away, and the Check Engine light was indeed now off. But the oil light was on. She returned to the station and they checked the oil and said the system must just be re-setting, and not to worry.

The oil light continued, periodically to come on (and the Check Engine light returned) but the temperature gauge never went above half-way, so we kept driving.

Then the car started billowing great masses of white smoke from the exhaust, and seems to have cracked the head or something horrible. My question is, how can an engine get so hot without the temperature gauge rising above half-way (it was at half-way when the disaster struck)?

Is that gauge measuring something other than the engine heat? Or is this explained by the original inspection station listing that we needed "an engine coolant temperature switch"? (Remember, the switch (1) informed that it had overheated when it needed the new radiator and (2) thereafter started at zero, rose to half-way after a mile or so, and stayed there.

(Is this the right forum to send a question like this?)

You have made some bad decisions and received some bad service. Changing the oil twice! What's up with that?

It sounds like you had a stuck closed thermostat which caused overheating and blew your cylinder head gasket. But...the problem could be something else. You need to get your car to a dealer or (better) a Volvo specialist before this chapter of accidents becomes a full blown death spiral. Do NOT take your car to random gas stations for mechanical work.

Thanks, migbro. Yeah, we've been prone to making bad decisions, throwing good money afer bad. The classic "don't have the money to do the right thing, so we get into a never-ending spiral of patches."

So a stuck closed thermostat itself can cause the engine to overheat? Or does it just make it so the gauge doesn't indicate that it's overheating?

I'm sorry you have trouble with your Volvo and I don't mean to be rude but it's clear from your questions you know very little about cars. Nothing I can tell you will really help you. The white smoke billowing from your tailpipe is a symptom of a serious mechanical problem which could be a blown head gasket or could be something else. At this point you should put your efforts into finding an honest Volvo specialist close enough to take your car to.

Well, I am interested on the outcome, or probable solutions to this problem.
Information and knowledge are porwerful tools..

Update on Volvo engine problem(s)
 

Hi Elchopperfreak. I'm afraid my responses tell a more and more embarrassing tale. We had the engine replaced with a used engine (by our local mechanic), and he told us that because oil had spilled into the exhaust system, we would spew more white smoke until it all burned off (or we could spend big bugs for a new exhaust system). The first week was very embarrassing with that smoke, and my wife even was stopped by the state police, who let her off saying they understood the situation.

Now it's several weeks later and (1) the smoke has pretty much subsided, (2) but not only is the Check Engine light back, but the brake light and "abs" (I think) light are also on. Our trusty mechanic told us not to worry about the brake and abs lights, and got the Check Engine light to go off by cleaning some dirty wires and connections. But it's back on after a day off peace.

We've never gotten the car inspected because the Check Engine light hasn't been off long enough. My wife is taking it over to trusty today to see if he can solve the Check Engine problem for good.

That is weird, did your "trusty" mechanic told you why it overheated? It will be the first thing to check after I put my cylinder head back together..
Ive read that the abs and brake lights could be caused by a couple faulty wires underneath the radiator, or if you have no speedometer it could be the ABS module.

A couple weeks for oil to burn off sounds odd..
Have you actually checked for codes and what they are?

Here is my take on this thread...

The initial failed inspection was due to a CEL. Likely cat and temp sensor codes.

The initial overheat had nothing to do with the failed inspection, but likely the rad leak which likely did show a high temp at the time. Most mechanics do change the t-stat and temp sensor after a car overheats but this one maybe did not. Anyway, when the car over heated it warped the head and caused a breach in the head gasket, thus the smoke, etc., out of the tailpipe. So, the initial overheat did the damage and the smoke, etc, is the result of that damage and the motor does not have to overheat any more to show those damage results.

As for the exhaust being dirty, that is understandable. One thing about that is, the cat is very unforgiving and will toss a code with only 5% of it clogged. There is a youtube video of a guy with hundreds of followers that claim it can be cleaned by driving with laqure thinner in the gas, a 10 to 1 mix. So, if need be, google that, I'm pretty sure the CEL code will be P0420.

Other than that, just get the codes read and deal with the issues one at a time. Old cars need work.

That scenario doesn't really explain the oil in the exhaust which would probably come from a failed turbo oil seal.

Design Flaw
 

Yes you can , and many have unfortunately experienced this design flaw. By the time you stop or read the coolant level low DIM message your engine is toast. The coolant gauge design is insanely flawed. The logic is just insane. They are programmed to stay in the middle for a wide temperature variation, deceives the operators into a false sense of security. Anyone can reproduce this issue by just draining the fluid and watch what happens next. There is nothing wrong with any sensor, or fan control or fluid used. Again just poor design, which has cost may owners an incredible headache. I suspect Volvo is once again protecting themselves from the ensuing liability claims if they were to acknowledge this issue. NOTHING LIKE DENYING A PROBLEM EXSISTS TO PROTECT YOURSELF IN COURT.

What an insensitive and misleading post. Your answere if you can call it that is not only wrong and misleading, but seems to any observer to be an attempt to mislead and deflect from the original question, which btw is of concern to many Volvo users who have suffered from this issue.