This post is for gear heads. I'm not going to simplify or gloss over details. Here's what Grover needed to be perfect.
Grover has a relatively new engine. While the engine was originally manufatured in 1959, or thereabouts, it was completely overhauled in 2011. As such the engine effectively has about 5000 miles on it. It had, in the past, run well but was plagued by a persistent but not constant missfire. I had for a long time suspected a minor electrical or carb tuning issue but never worked particularly hard to diagnose it. As my trip progressed it got worse to the point where at idle it had nearly a dead-miss on the number 4 cylinder and an intermittent miss on 3.
In Glenwood Springs, CO I started the process of correcting it. As my time at the moment is precious I decided to go the expensive but very diagnostic route of replacing virtually the entire ignition and induction systems. On the electrical side I replaced the rotor, distributor cap, wires and spark plugs. The distributor is electronic so no points or condensor to worry about. I also replaced the carburettor as the old one was dripping fuel from the accelerator linkage. I had previously moved from the mechanical fuel pump to an electric one to remove the possiblity of a failed fuel pump causing issues.
All of these changes had no effect on the engines performance and the miss persisted. GRRRRR.
As I mentioned on Monday, I had discovered an intake manifold vacuum leak. Vacuum leaks are typically diagnosed by spaying a petroleum distillate on potential leak sites and observing a change in engine rpm. This is exactly what I found when I sprayed the 3-4 cylinder intake manifold. I also suspected an exhause manifold leak because you could hear puffing and chuffing exhaust sounds at certain throttle settings (although this may have been a front pipe to manifold leak). The exhaust and intake manifolds use the same gasket. The idle issue I was having could very easily be caused by a vacuum leak so this was a postive development to identify something that could fix the problem.
On Tuesday morning I was trying to decide whether to drive to Silver City, NM, about 430 miles, or whether to attempt to fix the manifold gasket in Durango. Unfortunately I did not have a manifold gasket with me, something I will likely carry on future trips, so I would have to make a new gasket or wait a few days and pay a boat load of money to have one shipped. I went by Napa and purchased a sheet of exhaust manifold gasket and some copper coat and copper antisieze.
Exhaust manifold gasket is not like most other gaskets on a vehicle due to the extreme heat they experience. They typically are a fibre gasket with a metal core. This makes shaping a gasket from a blank sheet non-trivial as you are dealing with a composite material with a relatively thick metal core. I decided to invest in a Dremel to make the cuts.
Now I had my gasket material and a Dremel from Home Depot I need to find a place to work. You can't just do this level of work in a parking lot or on the side of a road. Coming out of the Home Depot parking lot I noticed on a hill just to the south an industrial building with a bunch of Jeeps parked in the lot. I decided to check it out. This would turn out to be the one of the luckiest decisions of my life (maybe a bit dramatic but that's how I feel about it today).
The industrial building was home to 4x4 and More, a local mechanics shop which specializes in offroad vehicles. Here's a link to their website.
www.4x4andmoredgo.com
I plead my case to the owner Lance. I just needed a place to do the work and I had my own tools and parts. He agreed and I set up shop. You can't just work in the full southern Colorado sun, your tools get too hot to use and you fry. So I set up my tarp as a shelter over the left front side of the truck.
I dug into the manifold and within an hour and a half had it disassembled. Here's a shot of the disassembled manifolds.
Unfortunately I found something no mechanic ever wants to see. Someone had put an incorrect bolt in the manifold. Right size, wrong thread. Now I don't want to sound bitter, but I paid good money for the engine rebuild and they put this bolt in the manifold? Words will be had with the shop responsible. Correct bolt on the right. You can see the mangled thread on the bolts that were the incorrect thread.
I ran a tap through the holes that had the wrong bolts and everything bolted up fine in the end. Seems that the metal in the head was harder than the bolt and the bolt suffered the damage.
Now I began the process of forming a gasket from the flat sheet of material. In this photo you can see the original gasket which has been traced onto the new material and I've begun to cut it out.
I used a cutting wheel, essentially a miniature grinder, to make straight cuts which approximated the shape of the outer edges of the gasket. I then used a technique I'd seen once on Youtube to cut the ports for each intake and exhaust runner. You hold the Dremel so that the cutting wheel makes a low angle to your workpiece and then cut at an angle through the workpiece so that the curve of the wheel matches the curve of the hole you want to cut. I then used various grinding and sanding attachments to smooth everything out and adjust the shape to perfectly match the old gasket. I then used a punch set, graciously provided by my hosts, to cut the bolt holes and locating pegs. Here's a shot of the final product.
Interestingly I ran the Dremel for probably an hour and a half off an inverter plugged into my auxilliary battery. Amazing how much energy is stored in a big lead acid battery.
I then began the reinstallation procedure for the manifolds. Land Rovers have a two piece manifold with intake and exhaust manifolds bolted together below the carburettor. The rusty looking one is the exhause manifold, the brighter one the intake. According to the Repair Operations Manual for the Series trucks, also referred to as "The Green Bible" the two manifolds should be first bolted to the head and then bolted together. This had apparently never been done for this manifold as the two were solidly fused together and had an original, metal gasket between them. Bolting the manifolds in the incorrect order can lead to improper mating and leaking manifold gaskets. This is likely exactly what occured with Grover. When I disassembled the manifold I found the faces of the intake and exhaust manifolds to be up to a sixteenth out of alignment. Interestingly this was also where remnants of the old gasket remained on the manifolds.
After reinstalling the manifolds, carburettor and alternator I fired it up to find no significant improvement at idle. At this point I was quite grumpy and it was the end of the day.
Thankfully at this point the fellows of 4x4 and More were done their day and came out to see how I'd faired. They quickly ran through the list of diagnostics attempting to determine the source of the miss. Eventually we rechecked the valve clearances, which I had set in Pincher Creek on my drive South, to find them a bit tight particularly on the number 4 intake which was the cylinder giving me the most trouble. After adjusting them properly (apparently a skill I will need to practice!) the engine was running much better but still randomly missing.
Next was timing. The timing marks on my Rover are quite inaccessible and require a good half hour of disassembly to see. They used a different method to set the timing, one with which I am unfamiliar and will have to read up on involving a vacuum gauge on the carburettor. After finding the engine approximately 15 degrees too far advanced and correcting the problem the engine ran perfectly. I don't mean just good I mean perfectly.
Enough said. A big day of work to correct numerous problems and the final outcome could not be better. I cannot say enough good about the fellows at 4x4 and More. The owner Lance and all the staff were welcoming, accomodating and extremely knowledgeable. If you are ever traveling through southern Colorado and need help, this is your shop. Now to go to the beer store to purchase some remuneration.
