View Full Version : No spark after overheat

Tampa Brad
11-22-2017, 02:57 AM
96 318ti m44 no mods

Had an overheat at idle that cracked the heater core running at the firewall. Repaired then ran good for a while. Car started randomly overheating at idle months later but not always. Water pump is noisy. Figured it was a sticky thermostat. Also discovered a small crack in an engine hose connection. Slow leak and I topped off as needed while I waited for parts. Also the fan doesn't seem to work but I figured it was the high speed relay issue I've read about so new relays are shipping with the new water pump, thermostat, belts, fuel injectors, fuel filter, and fuel pressure regulator.
Been driving it all week with no issues.

Today's breakdown
Doing 80 on the highway my temp suddenly jumped up. As I pulled over the the shoulder I started getting smoke and the car lost power and died right before stop. I was able to take the radiator cap off right away, water was not even warm. Shortly after that the level dropped and as I topped it off, it hit a hit spot and boiled up some. Once the car was cool and topped off it wouldn't start. I herd the starter rev but no ignition sound. A small pool of oil was under the car and the radiator fluid, that should be all water at this point was brown and smelled like exhaust(head gasket fml). Towed home, when cranked over the pullys all move, the valves move (looking through oil cap) but no ignition. I pulled 3 of the plug wires and put a spark plug on them but I don't get a spark.

This is odd since 6 months ago I replaced the coil pack, plugs and wires. Sorry for the chopy post, I wanted to try and keep it facts only. Thanks for your help!

paul somlo
11-24-2017, 09:06 PM
You've got so much going on, that it's hard to point fingers.

Based on the "Backstory", I'd say that overheating compromised the head gasket as the head warped and that much of what you're seeing is the result. You can test the fan - from what I remember, there are only two pins on its connector. If it's a brushless DC motor that drives the fan blades, you'll need to observe polarity. Figure out from wiring diagrams which is the negative terminal, and with a little creativity, you can use your battery to test it.

Tampa Brad
11-24-2017, 10:43 PM
You're right Paul, allot going on. Based on my tests so far I have come up with the camshaft position sensor as my main problem. If replacing that part gets her to start I'm going to test for a bad head gasket and replace that, if it's bad. Also fix all the cooling issues, again assuming it starts after the new sensor. Any tips of advice would help. Or if there is something else I should replace while I have her torn down to the heads.

paul somlo
11-25-2017, 02:25 AM
The camshaft sensor is an expensive part - unless you're absolutely certain that it's defective, you might think about getting a used one, maybe try Bavarian Auto Recycling. They don't fail often, so a used source is generally a good bet.

You're putting a lot of money into parts - if you have a DVM and a Bentley manual, you might be able to do some more in depth troubleshooting and save some money.

As far as "while you're in there", replace both cooling connectors and their o rings (sounds like you may have already replaced one). There's one on the block and one in the back of the head. Also, while you've got the valve cover off, replace the rubber seal for the oil supply to the cams (11121247948). You might also think about replacing all the coolant hoses that are impossible to get at without removing the lower intake manifold, which can best be described as tedious. Pretty much, anything plastic or rubber.

If you haven't already found it, here's a website that will come in handy:

What's the history on the car?

'96ti 240,000mi

11-25-2017, 02:30 AM
I'd have to agree with my Colorado based TI brethren, "backstory" is "today's" problem.

Sounds like you never fixed the overheating. I wouldn't trust that head further than I could throw it. I'd look for an entire new motor, but plan on replacing at least the head. Doesn't sound like a cam sensor will ultimately fix this.

You might be trying to dress up the pig. But the pig got blowed up. Maybe try to find a prettier, younger pig and put the lipstick on that one?

Tampa Brad
11-25-2017, 03:00 AM
You may be right. New cam sensor is 90 bucks at advanced auto. Almost all parts are returnable so if the new sensor doesn't give me combustion I'll return the parts and strip the car for eBay parts.

She's been solid for 3 years. 160k miles and everything else has worked perfect. Totally got my $2000 i spent out of her.

There's no real good way to test a warped block is there?

11-25-2017, 04:26 PM
Pressure test the cooling system so you know where the coolant is leaking.
Then do a compression test.
If engine is toast, I will not waste time rebuilding it.
As Bradestar suggested, get a younger pig.

paul somlo
11-25-2017, 06:31 PM
There's no real good way to test a warped block is there?
Sure - remove the head and use a good straight edge w/feeler gages. But, if there is warpage, I would expect it to be the head, not the block. And the head can be easily straightened/machined.

If engine is toast, I will not waste time rebuilding it.

Agreed - an engine rebuild is prohibitively expensive on the M44. But, from the description, it doesn't sound like anything beyond head work/gasket would be necessary.