Recent content by CJR

Here's my experience with heat exchangers and the trans coolers I used in my 88XJ & 00XJ. First I was formally trained to design high performance coolers(i.e.including fighter aircraft) and then went on to design many coolers for use in very high radiation areas. The "key" is manipulating the...

A quick check to confirm you have a bad ground at starter; 1. Connect a battery cable to the starter mounting bolt(i.e. starter ground). 2. Connect the other end of this cable to the NEGATIVE/BATTERY TERMINAL (i.e. ground). 3. Try to start engine. If it starts normally, you have a...

BMfinney, Your question; How can you tell if it is the head that is prone to cracking? This is a good question and I will offer my viewpoint based on my experience. Typically, cracks are caused by stresses. There are many types of stresses; tensile, compressive, shear and typically in the...

Some comments on cracked heads; 1. Years ago there was a company that had a reputation for their cracked car heads, and I had one. 2. All the cracks started around the hot exhaust valves. 3. I studied my cracked head and concluded the head exhaust ports were intentionally designed to raise...

After my last post I decided to elaborate further on the process required to bore an engine block; 1. When a new/"green engine block" is bored, the bores are round and straight but still have some residual stresses. 2. As the engine runs/thermally cycles, some of the residual stresses "relax"...

My personal comments on rebuilding/modifying internal combustion engines; 1. Many different brands of pistons use many different types of alloys; each alloy having different thermal expansions. 2. I NEVER BORE a block to some fixed increment; +0.040" etc. and then try to fit a piston to it. I...

To further discuss this problem let's list some issues; 1. Air temperature was stated to be 108F. The road air temperature was most likely hotter than 108F before it entered radiator to remove the BTUs from the radiator. 2. At cruise speeds, fuel consumption is low, i.e. fuel flow slows down...

Tim MN, With all due respect, I disagree with your statement on "vapor lock". I suggest you review;Taylor, Charles Fayette (1985). The Internal-combustion Engine in Theory and Practice: Combustion, fuels, materials, design. M.I.T. Press. p. 140-142. ISBN 9780262700276. Best regards, CJR

BattlebornXJ, Seems like you have trapped heat in the engine bay that may be causing "vapor-lock" in fuel lines,etc. As you are well aware, the intake manifold sits over very hot exhaust headers. Try insulation on the intake manifold, injector lines,etc.. Also, there is also insulation tape...

I put Borla cat-backs on my 88XJ & 00XJ and couldn't be happier. Likewise, I installed stainless steel headers on my 88XJ. Best regards, CJR

I had a similar problem that started suddenly with my 88XJ years ago and I suspected a cracked intake manifold. After many inspections of the intake manifold my youngest son's "eagle eyes" finally spotted the crack. Apparently, the previous owner had coated the aluminum manifold crack with an...

Jeepmedic46. When I bought my used 2000XJ I knew it was losing coolant. I pulled the head and had it pressure-tested and magnafluxed to be sure it was not cracked. Then I had it resurfaced/reground and I reinstalled it with a quality head gasket and new ARP head bolts. That was about...

"HB bolt"? I would suspect that something either broke inside the engine and is preventing rotation,i.e the crankshaft. Or something broke inside the transmission and is preventing the torque converter from turning easily. I would start first by pulling the pan and seeing if the crankshaft...

I had similar problems with one of my XJs. It was defective relays. Replaced the relays and my problems were solved. Relays are typically electro-mechanical devices and the contacts corrode and open the contacts/open circuits. Your fuel pump relay maybe opening and shutting off the fuel...

Alec5y6, Backfire could indicate a timing issue/worn camshaft lobes. I'd pull the valve cover and look at the valve lifts while the warmed-up engine is idling. A valve that has a smaller lift indicates a worn cam lobe. Likewise, the fuel injectors operate in a given sequence. The fuel...