F18Rep

Morning sportfans... somedays ya just can't guy a break and I'm having one of those days. I have a 951 in the shop for a reseal and some light upgrades. I've been puttering with it for a few weeks. It was running pretty well before we started but had bad oil leaks and some reliability issues.

We thought we would get pretty serious and do new sensors, MMs, clutch, Mtune, RMS, pan gasket, front seals, AOS, and rear balance shaft seals. We considered but had no reason to pull the head and risk a stud/broken bolt problem. Checked number 2 rod bearing and all is happy. All done, back together, looks beautiful, starts up and shortly dies. Water coming out of the coolant reservoir.

Did quick all-plugs-out compression test 125/123/120/125 and note that only #3 causes water to come out of reservoir. Arg. I think maybe the numbers are a little low but partly due to my forgetting to hold the throttle wide open.

I put a pressure tester on the reservoir and it held 15 lbs with no apparent drop or evidence of water entering the cylinder - can't really see into the cylinder anyway. Another weird little symptom: all have spark but only number 3 seems to want to fire.

Now, is there anything I can do before pulling the head to help ID the problem? Will a leakdown test help me? I'm worried we're going to have one of those situations where there is a tiny crack in the head or cylinder that opens up only with cylinder pressure....Bruce

DDP

Well a leakdown is a bit more comprehensive of a test and it's easy to do, so you might as well. Your compression numbers are not low for a stock car. More importantly, they're all consistent. What do you mean by #3 causes water to come out of the reservoir? Do a leakdown and see if the air is leaking down. If it's not going into the crankcase or through a valve, it's in your coolant and you need to pull the head.

Tedro951

Yeah, that's a little puzzling, especially if it wasn't puking from the coolant tank prior to the work. I'm also assuming the engine is no where near up to operating temp, since you mention it starts, then dies.

You'll probably have to do both, but if it were mine I'd troubleshoot the fuel or whatever issue causing it not to run, then move on to the coolant mystery.

F18Rep

Poor mans quick headgasket check...Remove reservoir cap, fill water right to edge of opening, put plug or tester in suspect cylinder (plugs removed from others) and crank cold engine. Reservoir "pukes." I did this same thing on the other clylinders and no puking. So I think I know there is air moving from the #3 cylinder to the coolant.
And btw, the engine will not restart. I think I will follow both of your suggestions though, try to get the other cylinders to fire and then do the leakdown. I've never done a leakdown so will have to study up on how to interpret results. Right off hand I don't see how it can add anything but I sure don't want to pull head, change gasket and have to put it together to find it wasn't the headgasket.

Other trivia: 88 Turbo, 86k, some evidence of overheat or abuse (melted AOS flange). And owner relates a story where the car was worked on by an independent who failed to reconnect wastegate line, the resulting test drive was incredible ("fastest car I have ever driven") but small fire occurred due to oil coming out of rear tower seal....Bruce

ausgeflippt951

Your comment about the AOS tells me you should also check the S&R sensors.

blown 944

If you are pressurizing the coolant via the cylinder then you either have a HG problem or cracked block. I'd pull the head regardless. A leaks own cannot tell you of you have a bent rod or may not be able to tell you if the block is cracked. Again I'd pull the head..

F18Rep

Well, heres the update. Once again, I can't quite explain it. I got the leakdown tester and a noid light. Leakdown instruction advise a warm engine so have to get it started. Starts finally but only on cylinders 3&4; 1&2 wont fire (I know bc exhaust is cold). Noid says trigger for the injector is present on 1&2. So I pull the 1&2 plugs (again). They are wet but don't smell like fuel. Water? Coolant? What else could it be? Dry them off, reinstall and she starts right up - all cylinders. Its running good too and, best of all, the open reservoir isn't puking.
Chat with the owner and he reminds me that aside from the puking thing (which I'm starting to think is BS), he has seen the same scenario play out. Won't start, fouled plugs, after some time seems to start & run like nothing ever happened.
Do you think I could have water in the tank? I can't explain how the plugs occasionally get wet....Bruce
PS... With the car running, Mtune appears to meet Rennlist reputation, at least for day 1.

Tedro951

I'd just drive it until you've run a new tank of gas through it and see.

Bri Bro

What comes to mind is that there are two wires running to the injectors even though they are joined together at the DME. So, 1 and 2 are on one wire, and 3 and 4 on the other. The wires then split again to drive the individual injectors. Even the injector power wires join up to a single lead inside the harness. I am guessing that your injector harness may be the problem. The act of checking it might have moved the wires enough to clear the problem. I would pull the boots back and look at the wires for several inches for cracked, missing insulation. At this point in these cars life, the injector harness all need to be replaced or at least cut back so that the wires and connectors can be replaced .

F18Rep

Brian...Thats a good thought, I've been burned by intermittent wiring problems before. Maybe I could get a peek at the place where the 1&2 split. And if I have time before my promised deadline I will wire on all new injector plugs, the only reason I haven't is that these are best looking harnesses I've ever seen. The wire insulation is still pliable, but you're right; maybe I should move it up from my list of nice-to-have stuff.

And btw, when I tested it with a noid light, something I almost never do, the light was kinda dim. It was a Bosche flatblade type noid (probably Chinese), but I'm not sure it the dimness is any kind of meaning.

At the moment, we're on the fence about doing the head gasket. Hope to get the leakdown done tonight. We'll prolly just man-up and do it though.

On the bad gas idea, I guess we're going to pump it down since we kinda need a new fuel filter anyway. We'll see how my mower runs on premium ;]...Bruce