When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The first time I assembled it a few months ago with the side gaskets, the sides didn't leak, it was the center fitting with the large o-ring that did. So I took it apart the other day and reassembled it without any gaskets, using just red sealant on all the mating surfaces, including around the bottom circle of the large round center fitting and around the o-ring goove, in addition to the o-ring. That's when the center section was good and the passenger side leaked.
So last night, had another one of my up until 3 AM work sessions, took it all apart again, removed all the sealant - that stuff bonds so well, how it leaks is beyond me - and put it all back together using both things that worked on each part from the 2 previous times. I now have gaskets on the sides with a smear of sealant on them, along with sealant in the o-ring groove, plus the o-ring, and around the bottom flange where it goes it. I'm letting the sealant setup for the recommended 24 hours and am then going to pressurize the system before adding any coolant to see if it holds pressure.
I think I might also have a leak at the rear passenger side fitting where it goes to the heater core hose, but when I removed the bolts to take it off and redo it, it was bonded so well from the first installation (gasket plus sealant) that I decided to leave it alone and put the bolts back in. That one I can access much easier if I need to change it if it's leaking without having to do a whole bunch of disassembly and I only had 2 of the trapezoidal gaskets on hand that I needed to use on the front bridge. We'll see what happens and I can order a couple more gaskets from Roger and fit that fitting next week if it turns out to be leaking.
Also, unless the head gasket is leaking right there in my previous picture, I don't think there is an easy way for the rear fitting to put coolant there. My car currently has the front wheels on ramps so it's canted backwards. Seems more likely that the front leak may have run rearward along that ridge than the back leak running uphill to get to that area, but we'll see. It's also possible that I do in fact have a failed head gasket in that area and the coolant was coming out from the head to block junction.
For those of you with experience, does that happen, or does the leak usually happen internally like when my 4.5L motor overheated and blew the head gasket, putting coolant into the cylinders.
Went to pull a vacuum on the 928 and it won't hold vacuum. The hissing sounds like it's coming from the same joint on the water bridge that I tried to repair last night, so the bridge must not be seating to the block well enough to seal.Gonna have to take it apart again and work on how those parts mate as Kevin and Stan have suggested. Both my wife and some believe the sound is coming from that area, which means it's probably not the head gasket, but we'll see.
i think it has no sense to put sealant around the big O ring at the WB. That one must work as the O ring principle… the more pressure , the more it seals. The O ring gets pressure from one side , deforms and lock itself against the sides. So yes, the big bore neck must be "clean" inside , without pitting or old leak residues. Sealant there will only help a very short time i'm afraid.
i think it has no sense to put sealant around the big O ring at the WB. That one must work as the O ring principle… the more pressure , the more it seals. The O ring gets pressure from one side , deforms and lock itself against the sides. So yes, the big bore neck must be "clean" inside , without pitting or old leak residues. Sealant there will only help a very short time i'm afraid.
When I took my old 4.5L motor apart after that head gasket blew someone had put sealant in there as well and that motor never leaked coolant. But that's not where my hissing sound / leak is coming from. It's from the passenger side bridge connection where the square opening is that's held on by 2 bolts. I believe the original leak that made me take it apart initially was the large round fitting with the o-ring, but that one hasn't leaked these last 2 times, but I also haven't gotten to the point where I could run the car either.
of course , as long as the big O ring can "deform" and do his job , there's no problem with extra sealant …. in that "big" gap , the sealant will do nothing. It is not compressed as between flanges.
I have here 2 types of waterbridges, the later one has confined "silicone" gaskets at the heads , the older one just flat gaskets.
of course , as long as the big O ring can "deform" and do his job , there's no problem with extra sealant …. in that "big" gap , the sealant will do nothing. It is not compressed as between flanges.
I have here 2 types of waterbridges, the later one has confined "silicone" gaskets at the heads , the older one just flat gaskets.
I used the gaskets from Roger that looked like thick paper with the red line of sealing material around the opening, then lightly coated both sides with sealant.
I wish there were thicker red silicone gaskets available for my older style water bridge, like exist for the oil pan and cam tower caps, as that would probably eliminate my issue. Maybe I should cut some myself.
Bulvot, thanks for the lead on that ultrasonic detector. I decided to buy one rather than borrow Chris'. Amazon delivered it this morning and it determined that the only air leak once I pull a vacuum with my Airlift is at the passenger side water bridge fitting and not at the head to block mate where I saw coolant between 2 & 3 - phew.
Full range leak detected even at minimum sensitivity
This engine has a weld repair on that part of the head. The integrity of the weld looks fine, but maybe the water bridge mating surface isn't perfectly square because of the weld and I may have to block sand it with a piece of glass as Kevin suggested to get it flat.
The other thing I could do is cut some silicone sheet gasket material that maybe would seal better than the factory paper setup. I have 3 different thicknesses on hand and would install these dry.
Here's an old OEM gasket that came off my 4.5L where the thickness is 1.6mm
I have clear silicone that's 1mm thick - probably too thin
Also have 1.3 mm black
And 3.4 mm black. With this being softer and thicker, maybe this one would make a good seal
Or I could use the OEM ones again and install them dry.
What do you guys think?
I've also ordered another large o-ring gasket from Roger and will install a new one of those as well.
before you add any gaskets please measure the parts as i suggested.
If the heads have been cut then the angle of the WB surface will be off,
better to get both parts flat first,
then you wont need a thick gasket.
before you add any gaskets please measure the parts as i suggested.
If the heads have been cut then the angle of the WB surface will be off,
better to get both parts flat first,
then you wont need a thick gasket.
Stan, yes I'm planning to do that before anything else. Currently working on removing the old sealant from the water bridge. The o-ring is pretty well covered so scrapping that one and have another on the way from Roger that arrives Monday or Tuesday.
Do you think the silicone gaskets will seal better than the paper with silicone line on them.
08-22-2019, 01:16 PM
