Last week I noticed coolant pooling on the top of my block--driver's side--right where the LIM connects to the block. I first checked the thermo housing and found it to be brittle and cracked--replaced it with a new one. I dried up the coolant puddle and ran in to town. Came back and there's the puddle again. There's no coolant leaking to the ground, just puddling on top of the block.

In the last week I've noticed that the car has become very hard to start--it's got normal compression pulling 18 inches at idle--it just starts like it's flooded. Being that it's a Series 5 I can hold the gas pedal in and get it started. Within seconds it's running normally. This will all tie in to my question.

Back to the puddle. I pulled the UIM off and check the coolant lines off the back of the block, the BAC and the water pump. I had just replaced all rubber with silicone and I'm pretty sure that it's not the hoses. I'm about ready to give in and admit it's the LIM o-rings that I'll have to replace.

Now, my question is, would coolant leaking from the LIM work it's way into the combustion chambers and cause a flood/non-compression startup issue? If not, I'll have to fix the leak then figure out what's up with my start up.

Thanks all!

B

 

I am a little rusty because I haven't played with my car at all but where does water run through the LIM? I was going to say it might be the BAC line to the back of the water pump housing but you said you checked that one.

 

bump

 

I vote LIM coolant rings

 

Dude... The LIM and UIM should mate somewhere on the PASSENGER side of the car. And no coolant that I am aware of goes through the LIM. If you got coolant on top of the keg, its coming from the 90 degree hose under the TP, or in the thermowax are.

 

Is this an S5 thing? Cause I have never heard of LIM coolant rings..

Edit:

Ive done an S4/S5 HYBRID and STILL dont know WTF you are talking about.

 

Turbo engines have them.

 

look at where the coolant supply line for the turbo comes out of, of pull off your UIM and you'll see what he's talking about. 4 intake ports and 2 coolant holes in between.

If the lines to your throttle body are secure, make sure its not leaking from the back of the waterpump housing, if it isn't, the only other place for coolant in that area would be the LIM.

 

My advice to anyone running the coolant throught the TB is to make the lines longer and replace the claps with the Stainless steel screw type, or ATLEAST use the better claps. I had a problem with BOTH the line coming out of the block on the back and the one going to the water pump, both areas where leaking. So I got better clamps for them.... The stock ones get weak over the years...

 

Okay, those lines I am aware of. But there is NO coolant going through the UIM. For some reason I thought he was trying to describe a seal that went between the UIM and LIM.

 

Thanks for the replies. I'm pretty certain it's the coolant rings, but what I'd really like to know is if leaking coolant can cause a temporary startup condition--coolant in the combustion chamber?

 

Bump.

 

depending on how much its leaking, it is right next to the intake ports, so if the rings and the gasket are leaking enough for it to get on top of the block, then it could be leaking enough to run down into the intake ports i guess. I am leaning more towards one of the lines on top of the block though as i have never seen a failure resulting in coolant on top of the block from the LIM

 

Yep, those 2 o-rings are most likely the problem.
Mine never leaked into the intake path.
Speaking from experience, don't put it off! The leak will get bad enough that coolant will run right through the spot where it is weak.

 

The car is garaged and I'll be pulling the LIM and turbo off shortly. Anyone have part numbers for the S5 o-rings and the gasket for the UIM>LIM?
While everything is off I think I'll get the manis polished, along with the TB and Alt.

 

Yeah on a Turbo there is only that Oring going through the LIM to the turbo and then the Coolant hole on the pass side rear housing which goes to the back of the TB for the thermo wax.

Check the Mazdatrix website for those Orings.