What causes head gasket failures?
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Three Wheeling
Joined: Jul 2018
Posts: 85
Likes: 3
From: Las Vegas, Nevada
What causes head gasket failures?
Howdy everyone. Curiosity has struck me again and I am wondering what causes head gaskets to fail on these discovery 2's? Is it from running too hot, or overheating? I'm thinking of installing 2 16 inch auxiliary fans one in front of the radiator to cool it and blow air over the transmission and engine oil coolers and one on the back of the the condenser to act as a second puller in between that gap, to suck the heat out and help the a/c too! I'd have 2 independent thermostatic controllers I found for each fan! One probe would mount in the radiator hose on top and the other in the transmission cooler or condenser! 1 thermostat would set at 197 degrees fahrenheit and the other at 212 degrees fahrenheit overlapping set points for strenuous times, like towing my future travel trailer where one fan can't keep up with the heat! That and I'm buying my new upper hose assembly and 180 degree thermostat to keep my stuff cool along with a 70/30 coolant ratio! Is this a good plan? If my system works my over all system temperature sitting at mcdonalds with the A/C running, on a 115 degree day won't budge from 190-196 degrees! These fans are rated at 3000 CFM each! Including the factory condenser and mechanical fan I'll have four cooling fans to prevent catastrophic engine failure. Sound good folks?
Baja
Joined: Aug 2013
Posts: 5,845
Likes: 368
From: Near Bordeaux, France
What causes head gasket failures?
Generally overheating for various reasons. The heads become warped and once this happens it's an ongoing nightmare. You have two choices once it's seriously overheated, skim the heads or replace them. Alloy heads on iron blocks always warp when overheated.
Generally overheating for various reasons. The heads become warped and once this happens it's an ongoing nightmare. You have two choices once it's seriously overheated, skim the heads or replace them. Alloy heads on iron blocks always warp when overheated.
Recovery Vehicle
Joined: Jul 2012
Posts: 976
Likes: 154
From: Mideast US
Cooling system designed with no overhead for aging or minor decrease in coolant level.
And owners who think they bought an airconditioner with wheels; looong idling times while parked waiting for something in total comfort at 100F ambient temperature instead of shutting off the Rover and walk to a shade...
And owners who think they bought an airconditioner with wheels; looong idling times while parked waiting for something in total comfort at 100F ambient temperature instead of shutting off the Rover and walk to a shade...
Camel Trophy
Joined: Dec 2009
Posts: 3,884
Likes: 951
From: Charlotte
I'm not an engineer, but based on reading this and other forums for many years, and seeing the failed headgasket on my truck plus seeing the design, I'd say as others have that it's overheating the engine that does it, combined with the fact that the coolant passage from the block to the head is at the very rear of each head and the gasket is only about 1/8" wide in that location. Some headgasket failures are reported in other locations, but I'd guess a significant majority of failed headgaskets are leaking from the rear.
Winching
Joined: Mar 2015
Posts: 623
Likes: 44
From: North Alabama
I guess I'll ask the dumb question, if overheating causes the head gasket failure, what causes the overheating?
If I'm building / shopping for a new D2 engine, how do you lessen the likelihood of overheating and failed head gaskets?
If I'm building / shopping for a new D2 engine, how do you lessen the likelihood of overheating and failed head gaskets?
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Three Wheeling
Joined: Jul 2018
Posts: 85
Likes: 3
From: Las Vegas, Nevada
I'm not an engineer, but based on reading this and other forums for many years, and seeing the failed headgasket on my truck plus seeing the design, I'd say as others have that it's overheating the engine that does it, combined with the fact that the coolant passage from the block to the head is at the very rear of each head and the gasket is only about 1/8" wide in that location. Some headgasket failures are reported in other locations, but I'd guess a significant majority of failed headgaskets are leaking from the rear.
yeah I just got new that my friend who’s the previous and first owner did the head gaskets and everything. Although it’s over heated 3 times due to a faulty upper hose it was shut off each time and when I put water in I doesn’t smoke or anything so I got away unscathed! Lucky me. I just gotta order that and the new thermostat! I’m using Prestone long life green coolant. I’m gonna run a 70/30 mix for better cooling. The truck works excellent! Should I do a prestone cleaner flush? Should I also add water wetter too?
Camel Trophy
Joined: Sep 2017
Posts: 3,818
Likes: 1,337
From: Mission BC Canada
Not much you can do, mechanically, it is really a maintenance issue. Modern "iron" engine designs are very durable and largely overheat tolerant. You can still kill them with an overheat but it is less likely.
On Disco's it is pretty easy treat it like a 14+year old truck:
- Monitor the coolant level and state
- This one is debatable but go away from Dexacool to a green replacement
- Monitor your engine temps - don't let them get to overheat generally 220 is getting too high
- add a 180 deg thermostat
- check your hoses every 6 months hot and cold
- I check for leaks any time I fuel up, after driving any distance - mostly throttle body heater but a general keep an eye on things
- Coolant is not forever change it very 12 to 18 months
Finally know your own truck everyone is different mine runs 188 - 197 on side roads and will get up 203 - 207 on long steep up hills for 3 or 4 minutes, until the fan clutch kicks in.
Note this is a hot weather issue, with outside temps in the 28 to 30 def C range
If I hit 215ish, I would pull over because that is abnormal, and would warrant looking at what is going on.
