Today I was working on my friend's s4 TII engine that cranks over but doesn't start.

We did a compression test, and got zero compression on both rotors. The previous owner mentioned that it needs new water seals, but I'm wondering if blown water seals will cause the engine to have no compression. What else do you think may cause the car to have no compression? I already searched....

 

Any water come out of the plug holes? That would be amazing (no compression on any face), if you're using the gage right...Do an audible comp. check just to make sure...How's the coolant level been doing?

 

IS the coolant system pressureizing instantly when you turn the car over? If so then you may be right.

Why are you testing the car? Did it suddenly quit or was it sold to you that way? How long has it sat? It it has been pretty long then I guess it's possible the apex seals rusted to the housings and got ripped out when you turned the engien over.

Also one last thing are you testing the rotors using the leading plug holes? (the bottom ones) and are you depressurizing the gauge as you turn the motor over?

 

It's possible that water was coming out. When we removed the spark plugs, they were pretty soaked in what we thought was gas. But now that you mention it, it seems to be more characterstic of water. What does this mean? We didn't check the coolant level.



I don't know if the coolant system was pressurizing.

We are testing the car because the previous owner(who swapped in the tII motor, a seemingly pretty knowledgeable guy) said that the water seals needed to be replaced. The car would run, but quickly overheat before we bought it... then it stopped working altogether for reasons that I'm not quite sure of. That may be why we decided to test the compression. It has been sitting for several months(3-5).

Also, we used the top spark plug holes. That's what we were told to use from a video that my friend had bought. Were they the wrong ones? ...and would they give the wrong/zero numbers?


Thanks for your help so far guys. Anyone else care to chime in?

 

yeah..0 compression all rotor faces = REALLY FLOODED. Start injecting MMO.

 

Jesus Christmas. 0 compression on both rotors either means that it is very flooded with gas, or very flooded with water. The flooding of the water could have caused all of the apex seals to bust due to hydrolock. Happened to a friend's car once.

 

Jesus Christmas. 0 compression on both rotors either means that it is very flooded with gas, or very flooded with water. The flooding of the water could have caused all of the apex seals to bust due to hydrolock. Happened to a friend's car once.

 

I see..

So the busted water seals isn't the cause of the zero compression? The water flooded, and caused the engine to hydrolock, which blew the apex seals. The blown apex seals is what's causing the zero compression. It all makes sense now.

So I guess we'll have to replace the water seals and the apex seals... I hope nothing else is broken. Do you think anything else might have been affected from the hydrolock?

Edit: Also, what is MMO?

 

marvel mystery oil, it's sold at almost all car stores - advance autoparts, autozone etc.

 

As far as I know, rotaries cannot hydrolock. Ever heard of the water trick? Some people dump water straight into the engine while its running to "steam clean" the carbon out. Kind of a substitute for the ATF trick.

crzycav86, I would be willing to bet that the engine needs a full rebuild. If the water seals are gone, a rebuild is definatly needed.

-Joe

 

If this thing's been sitting for a couple of months with water in it, you've got a whole lot of work ahead of ya, not to mention the wallet's going to be much lighter when it's done...Do you hear any "rubbing" or "scrunching" sounds when the engine is turned by hand (put a 19mm or 3/4" socket on that front pulley bolt & turn clockwise)...If the rotors & housings are rusted up in there, it's beyond hope for a quick fix...

 

just push start that sucker......im 95 percent sure it will start on your first try if it is FLOODED with fuel..not water. if its an apex seal problem then rebuild time.

 

I bought my car with bad coolant seals two years ago. I didnt know what was wrong but i knew it wouldnt run. It made 0 compression when i bought it. So yes bad water seals could cause no compression. We pulled that bitch for about 30 minutes one day and it started and ran just fine. I used block weld and drove the car for a year and a half that way. Every 3 or 4 months the block weld would start to give and allow water into the housings. it gradually got worse and worse untill it would not start unless you pulled it. I used block weld again and off i went. I didnt replace the motor b/c i was collecting parts and saving for a turbo swap.

 

It sounds to me like you guys are probably wasting your time on that old motor, one way or another. Since the owner already told you the water seals are shot, we all know what that means. You shoulda just started wrenching on it to get it out of the car, rather than fighting with it.

Water seal motors are the worst to try and rebuild, if anyone has let them sit for 2 or 3 months. By definition, water seal motors allow water to get into the combustion chamber (where there are all these clean, shiny metal surfaces). IF you just let the bitch sit there for a while, quite a bit of water pools up in there. OF course water + bare metal + time = rust. So you wind up with an engine full of rusted, siezed seals and parts.

Even when they'll still turn, the seals are often rusted partially in place and don't seal well enough to perform their duties in a working engine. Since some of the apex seals will be in the out position and some in the compressed in position when an engine is shut down, it is easy to see that if they stick in place the engine either won't turn at all (if the extended seal won't push back in) or an engine with low or no compression in some areas (if the compressed seals won't expand back out).

Even if you do somehow restore compression, how good to you think the engine will be? GIven that you already know it has a water seal issue?

 

**** it.. Try to start it anyways... Whats it gonna hurt?

 

Waste time, that could have otherwise been spent dropping in a replacement engine?

 

Pfft...

 

hmm.. ok may be off topic but if a car sits over time will gas seep into the oil? or is that only caused by leaky injectors/flooding?

 

I have figured out that if you premix with anything more "potent" than about 100:1, a little gas/premix in the oil is a normal thing, even on a rebuilt w/ new oil control rings. It doesn't bother me much, for one, it means the rotor housings are getting more than adequate lubrication, and two, it isn't enough over the life of the oil change to do any damage...In answer to the question, if the car is just sitting, no gas should be getting into the oil, if the injectors are good...

 

the reason i ask is that i just acquired an 89 parts car (very nice, and i get the motor and am parting out the rest) and i was told that the rotors have low compression and the oil smells like gas, i mean relaly smells like gas. it only had 108k miles on it and i am thinking that the guy who had it had no rotary knowledge and salvaged it when it was only severly flooded. i have to check the rotors tomorrow and see if they are ok (no broken apex seals anything like that) only reason i asked.

 

Thanks Resurrection, that was insightful.

It's not my car, it's my friend's car.. but I think we're still gonna try to fix it.. Frankly, we don't have anything much better to do during our summer vacation.

Anyway, I suppose all of my questions have been put to rest for now. Thanks a lot.

 

Absolutely hydrolock. For kicks a few years ago, I pulled a junkyard 13B, washed and disassembled it. Before disassembly, I was power washing, and later having fun pumping water through the rotors from a garden hose

You can't crank it once you fill an intake gulp completely with water. It won't turn at all by hand or wrench. I imagine it would turn with great force. Apply enough force and soft seals start letting loose, apply enough force fast enough and I figure hard seals will bend/break.

Engines compress our gaseous mix before ignition. So with an 8.5:1, for example, where do you think 8.5 atmospheres goes? This gets compressed. Liquids don't do the spongy compression thing that air does, so we start breaking things.

That's not water used in the flushing trick you mention, it's guys with leftover vinegar enema/douche from playing **** games with the boys at the bathhouse.

 

Was just going to say that you dirty lil rat