Leaking Coolant Pipe from Bad Hose Routing
Joe Angell
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I started noticing coolant leaking under my car. It wasn’t a lot, so I ignored it for a while, but I finally put it up on the lift and took a look.
Finding the Leak
After my otterstat gasket failed a few years back, I’ve been running with a custom pipe a friend of a friend made for me. My EFI conversion doesn’t need an otterstat (MegaSquirt runs the cooling fans based on the 3.0L water pump temperature sender), so the new pipe omits it.
This worked great. The problem is that I ran the pipe on top of the frame for some reason, probably because it took me so long to do the 3.0L swap that I forgot how it routed. Curiously, the original pipe was running under the frame, but for whatever I put this one on top.
After a few years of vibration, this wore a groove into the pipe, eventually puncturing it and causing a leak. But the leak was partially sealed while resting on the frame, and when the coolant got hot the pipe would expand and the leak would seal completely. I had gone on a day trip (a leaf tour with the New England Regional DeLorean club — lots of driving) with four spare bottles of coolant in my car, and I never needed any of it.
But the day I had it on the lift, it was pouring coolant down the subframe. Lifting the pipe just made it worse. I needed to replace the pipe.
This groove was worn into the pipe from it resting on top of the frame instead of being secured under it.
Since I don’t know how easily I can get another one of those pipes made, I ordered one of the new style pipes that some of the vendors sell. It comes with a pre-installed screw-in otterstat, so there’s no clip to fail and the gasket won’t leak. It also comes on at 198 degrees instead of 207 degrees, which will keep otherwise stock cars cooler than the old temperature switch.
I don’t need the otterstat, so it’s just a glorified plug, but it works fine here. Maybe I’ll hook up the otterstat as a fail-safe for the EFI conversion (although if the EFI computer fails I’ll have bigger problems), or just a secondary temperature indicator for some future mod.
The poor routing also put the driver’s side water pump hose very close to the A/C compressor pulley, to the point that the shield was ruined and there was an actual nick in the hose. I ordered a replacement for that too, along with new hose clamps, the cushion clamp for the otterstat pipe, and the mounting bracket for the water pump hose.
The pipe is on top of the frame, and the hose is right next to the compressor pulley.
A close up of the nick in the hose from the compressor.
Installation
Replacing these parts was straightforward enough, mostly. Just loosen some hose clamps, then put in the new parts and tighten them up.
The biggest problem was that after installing the cushion clamp, the otterstat pipe rubbed against the frame, just in a different place. I could shift it a bit, but then the hose rubbed against the frame.
You can see that when using the cushion clamp in the “correct” hole, the pipe rubbed against the frame. Reference picture courtesy of Adam Harriot.
Luckily, there was a second hole in the frame, more rearward and closer to the engine. I don’t know why this was there, but once mounted, the pipe and hose cleared both the frame and the compressor.
The two holes in my frame. I don’t think the rearmost one is in most cars.
The hoses and pipes clear everything when I use this alternate hole for the cushion clamp.
The second problem was the hose clamps. The ones I’d ordered were too large for the otterstat pipe, but they worked for the water pump end of the hose. When completely closed the clamps still weren’t tight on the pipe. I had some properly-sized and more robust clamps in a drawer that I used instead.
The top hose clamp is too large, as can be seen from it being tightened on the right. The good clamp is more robust and, more importantly, the right size.
The last problem was the bracket for the water pump. There doesn’t appear to be a place to mount this on the 3.0L engine. Since everything clears everything else, I decided that it wasn’t necessary and tossed it in a drawer.
The 2.8L engine on the right has a place for the hose bracket, but the 3.0L one is missing it entirely. Reference picture courtesy of Adam Harriot.
That was pretty much it. I didn’t have to bleed the system because of the self-bleeder kit. I went out for a drive and the leak was gone. I’ll have to come up with something useful to do with that otterstat, but that’s a project for another time.