Hi all,

New to the forums. I've been reading through quite a few of the CNG threads around. I'm looking for a few answers that are missing.

I'm about to purchase a 2000 E350 with a CNG set up 5.4L. Vehicle has about 130K miles. Catch is the engine is blown. No idea why, i don't blame the CNG, not really concerned. What I'm thinking however, is if I have to pull the motor for a rebuild I may as well explore my options. 5.4 engines are a dime a dozen (relatively speaking) and finding a crashed e-series van from which I can pull a harness isn't hard.

I know I will get some responses saying I should just swap in a repaired CNG motor and leave it be. It's an option. However, I'm more interested in boosting a 5.4 gas OR swapping in the 2V 6.8L. Eventually I will make this a 4x4 and having a gas motor seems the wiser choice when away from large metropolitan areas.

Outside of replacing the long block, the wiring harness, and returning an actual gas tank what else needs swapping?

I've spent a bit of time trying to find out what goes into a CNG swap but I haven't found much useful information in this situation. Significantly less information about reverting back.

I should say too, not buying the van and instead buying an already gassed one isn't an option. I'm looking at 300 bucks for the vehicle. Can't really pass that up.

Thanks in advance,
Spencer

 

Driving a LPG converted 5.4 myself, I would say stay with the CNG one. But I dunno about the avail. of CNG in your area.
I'm not very familiar with the factory CNG option offered by Ford, but usually the only hardware difference is the valves and valve seats. Since CNG and LPG burn slower than gas the heat transfer from the valves to the heads is the main issue, therefor hardened seats and more heat resistant valves are used.
Often enough you'll find these in gas engines too and don't need to convert the heads. Here in Europe about 75% of American V8's run on LPG due to gas prices being 4x higher than in the US, but LPG being half that. 90% of them run the stock valves and heads and a few add some chemical shots to lube the valves (which is very questionable).
My 5.4 runs the LPG as a piggyback system, meaning all gas stuff is still there and fully functional and as soon as the coolant temp reaches 40°C the gas injectors shut off and LPG injectors take over. That gives me the advantage to still have a 34gal. fuel tank and an additional 28gal. LPG tank where the spare tire used to sit and being able to switch between them as I like.
So if I were in your shoes, I would check if there are different heads and valves for the CNG engine. The block itself should be the same anyway. That means if your heads ar ok, go with a new block and be done with it.
If you convert to gas, you might need a whole injection system, harness, gas tank etc.

 

I hear you and I'm the same way; but, how much is a running van the equivalent of what you hope to accomplish swapping a good engine into this $300 CNG van? Say you find a V10 van in good running order for $3000. You're about half than in parts and the other half is the 50-100 hours in the swap; 20 hours wrenching, the rest poring over wiring diagrams and specs. How much can you get for the CNG van if you get it running? Maybe you can swap it for a V10 van.

I suppose an ECU is included when you say harness. Will the CNG tranny work with a gas ECU? Do CNG vans have substantially different gearing?

If you stay with CNG, how much time is left on the tank/s? It's that cost that keeps me away from CNG. Maybe it's not a factor in an off-road only vehicle.

Sixto
93 E150 Chateau 5.8 192K miles

 

A running van with the service records and body condition of this van would be in the 4-5K range based on my search thus far. So even if I buy a 3K engine I'm still ahead in the cost department. Personally I think 3K is a bit high as I can find a junk yard motor for somewhere in the 2-300$ range. (couple of really nice local places). and rebuild for about 1K, I'm thinking slightly better than stock parts.

In terms of time, this would be more of a side project for fun. My end goal would be in the Sportsmobile or Quigley arena. Most likely doing my own work as I find their prices to be ridiculous and I have access to a full machine (with welders) and mechanic shop.

Yes.

The CNG, Gas, and v10 engines all use the same trans in the 2000 model E350. it's your bog standard 4r100. From speaking with the seller the trans is in really good shape. Although I'm not worried about the trans as I would likely try to find a 4x4 F150 that's been totaled and pull the 5.4 with the trans and transfer case as I would like to eventually go 4x4 with this.

No. Still the 3.73 or 4.10. I'm leaning toward the 4.10 as I'd like to have towing option still available.

The driving force for the back to gas conversion is the ease of availability of the 5.4 gas motors as well as the fact the CNG tanks have expired. I don't know what the cost is to get them re-certified but I do know I can sell them for upwards of 500$ based on eBay searches. Even if I sold it for 300, I'd be even on the overall purchase. Heck, I could buy the van at 300 tow it to the local junk yard and he'll give me 600 for the scrap value. It's kind of a no lose situation.

My issue with the conversion isn't about my ability to wrench on the van. That's easy and straight forward. My issue is knowing what all Ford did from the factory floor that separates the CNG version from the Gas version. Once I know what all parts are added/subtracted/different I can then get them in the right order.

Thank you

 

Thanks for the feedback. I live in Los Angeles right now and there are TONS of CNG stations. I have two driving reasons for swapping to a gas setup. First, the CNG engine in the van is blown. I have to put a replacement no matter what, may as well use a petrol motor. Second, the CNG tanks need to have a Department of Motor Vehicles (DMV) certification. The certifications last for a number of years; this one is expired and the cost to get it re-certified is not cheap.

The piggy back systems are great with one draw back. We don't use them in the states. To be frank I think it would confuse most Americans to have to fill two tanks. Don't tell them I said that.

As an aside, the LPG piggy back system is really popular in Brasil. I was speaking with my sister-in-law's father about them a while back. Seems that even though they are popular you have to be careful when running LPG. The efficiency of a LPG burn is less than that of petrol and therefore you actually end up spending more per mile to drive on LPG. That said, gas prices in Brasil are quite a bit cheaper than both Europe and the states.

Third reason I'd like to switch back to petrol is I plan on boosting this motor. I don't know how well CNG likes high compression.

 

These days trying to convert a factory-built system to something entirely different involves a lot of work and specialized knowledge they typical vehicle owner doesn't have and isn't equipped to deal with.

Along with fuel delivery you'll have many, many chassis wiring differences that would need to be addressed. This can be as "simple" as re-configuring a few of the factory connectors to complete wiring harness and ECM swaps that tax the patience and skill of experienced mechanics. In fact there are one or two threads here involving motor and fuel-type swaps----they're amazing if only in the scope of what's involved.

One reason there seem to be missing answers is this sort of swap isn't practical and the wiser among us know to leave well enough alone. Speaking only to the practical and "easily doable" side this sort of swap should be avoided because its NOT easily accomplished. While the idea of a "cheap" van is alluring however if the one is available for only $300 as is it could be scrapped out or parted out for a tide profit which would then be used to purchase a turn-key van better suited to your real and present needs.

 

Did you ever attempt this project?
It looks like gasoline fuel injectors, perhaps the fuel rail, fuel lines, fuel tank and fuel pump, fuel filler neck, and one of the ECMs need to be swapped over to the gas one (or maybe it's possible to flash / re-program the CNG stock one but I don't know).
I'll be trying this myself this year.