Adam Poland

I just recently added another '86 951 to my garage, and I'm having a very confusing issue. I pulled it in to my shop under its own power, and decided to take off the intake and replace the gaskets. (a job which i have done many times). I put it back together, exactly the way it was. I go to start the car to drive it down the road, and it won't fire. It has spark, and is getting fuel. However, it did have an aftermarket alarm system, which I removed, and bypassed the "factory" connector that was in there. But my car isn't a car with a factory alarm system? Car still will not fire. It has fuel, and everything necessary to start, but a hidden problem is keeping it from starting....PLEASE, ANY SUGGESTIONS WILL BE GREATLY APPRECIATED. I would love to get back in the car, so I can quit driving the Mini Cooper...(non-s).

George D

You may have leaks in your intake at the gaskets. Have someone turnover the car while you spray wd40 or starter fluid to see if it gets sucked in at the gaskets. How do I know this?

PorscheDude1

Check the speed and reference sensors?

KuHL 951

^^+1 Check the sensor connectors, you probably bumped them and they are very brittle.

fortysixandtwo

Does the tachometer move while cranking? If not, its probably the speed and reference sensors causing your problem.

Adam Poland

Thanks for all the input so far guys. I'll definitely have to give the sensors a try.

Adam Poland

Ok the sensors fixed the problem, but i drove it down the road and back, and it ran fine. Then i parked it, and did ABSOLUTELY nothing. I go to start it later, and it wont start. At this point we are baffled, so we take it to Fifth Gear in Lewisville. They cannot find any problems. They just say the car has almost zero compression. Could i have blown a piston ring or head gasket when i drove it? I didnt drive it hard, but when it got into boost one time, there was a huge cloud of smoke behind the car, but I think that was from a major oil leak. Im stumped...

Chris White

Can you be a little more specific on the problem? Does it make any attempt to fire? Backfire?
Any burps or farts?
How do you know its getting fuel?
What do the plugs look like?

You disturbed the wiring harness when you removed the intake manifold – that’s the first place I would look.

I would doubt that it has Zero compression – maybe low compression. If you get a very low compression reading squirt in a couple of table spoons of oil – that will temporarily seal bad rings and give you a reading.

Based on the cloud of smoke when on boost you might have some tired rings that are allowing a lot of blow by when under boost. That pressurizes the crank case and blows oil back into the intake.

reno808

make sure the spark plug wires are in the correct order

sebastian944

+1 on injector harness, i had that problem

Adam Poland

Well the car seems like it makes a weak attempt to fire, I mean hardly at all. The plugs looked pretty fouled out and we replaced them, still no start. I think the rings could be bad, there is tons of oil throughout the whole intake system, more than average in the turbo, and a lot in the intercooler. When you take out a hard pipe, a thin stream of oil spills out.

Chris White

It does sound like the rings are worn. It still should be able to fire.
It could be a lot of little things adding up to a no start – weak plug wires, worn rotor, low voltage, worn rings…and a wiring issue.

You could start to go through each of those….or you could squirt a little ether in the intake manifold and see how that works (be careful with ether…)

Adam Poland

Found out the problem. Ended up dropping out the engine and breaking it down. Rings are completely blown, and the #1 piston is burned. The cause? Cycling valve was broken into two pieces, causing the car to overboost. I knew that it had to be running 2 BAR of boost for some reason....

pudges951

Ouch... not good, going for a stock build up or something better??

ramius665

Suuuuuuuucks... Going to keep the car or part it?

I just did a rebuild on my 951 and it wasn't all that difficult, but MAN does the prices of parts add up quick. I think in the end I spent about $8k to do the full rebuild.