18 Oct 2024

The plan:

A few years ago (more than a few), some friends gifted to me (maybe: “handed off”) a rather-clean ’84 245 DL. It’s an original car, 200k miles, M46, not much in the way of options. Left front fender was wrinkled from a parking lot accident.

My wife owned an ’85 DL sedan in the early days of our relationship and I got a bit of an education working on that car. I decided I’d like another 240 someday, and shortly thereafter we were offered the 245. Once the trio of finances, time, and storage space aligned, I used two days of a three day weekend to pick up the new family member.

In an earlier life, I gained a fair amount of experience working on Ford 3.8 V6s. Ford made several variants of this “Essex” (that’s Canada Essex, not UK Essex) motor: a carbureted and later CFI (or throttle body injected) version, an MPFI “single port” version, a later “split port” version (long and short intake runners per cylinder), split port 3.9L (almost identical to the 3.8), and a split port 4.2L version for Ford trucks and full-size vans.

Many folks consider the Ford Essex motors to be (inferior?) copy-cat versions of the GM 3800 / 4300. And maybe that’s not completely untrue but it’s certainly more nuanced than that and not worth getting into here. I have quite a bit of experience, at this point, keeping these motors running and that leads to my Great Plan for the ’84 245, a new take on the 5.0L V8 swap that is reasonably-common in the Volvo 240 world: the Essex 4.2L V6 swap.

There are benefits to using this motor over some others, aside from the fact that I had it (and a lot of accoutrement): first, it’s a few pounds lighter than the 5.0L and, in a light vehicle, should net better fuel economy than a V8. It’s also shorter than a 5.0L so -in theory- it will have less weight ahead of the front axle centerline than a V8 motor. And in terms of the Essex vs. other V6s, since it was used in vehicles that also had 5.0L options, there are motor mounts that “look” just like those used by a 5.0L and appropriately position the engine in the car.

I like to answer the job interview “describe one of your weaknesses” question with: I have a hard time saying no to free engines. I have a complete 3.8L single port motor with MAF conversion and AOD transmission, a 3.9L with spun rod bearing from a 5-speed ’04 Mustang (no transmission), and a 4.2L with 4R70W from a ’99 E-150 full size van. All of these motors are about the same externally, and since I had everything to accompany the 4.2 including accessories, wiring harness and ECM, and other goodies, and since the ’99 4.2L is good for 200+ HP and ~250 lbs torque, it seemed to be the natural fit.

Here’s the work I’ve done thus-far:

Motor mounts:

I fabbed up a pair of chassis-side brackets based on the diagrams for some 5.0L swap brackets that are floating around the internet. These brackets accept engine-side mounts like those that are found on Fox-body Mustangs (and maybe other cars too). Because of that, they also accept engine-side mounts like those that are found on 3.8L V6s, and since the mount bosses on all Essex blocks are essentially the same, attaching 3.8 Mustang engine mounts to the 4.2 is a trivial process.

Engine / front subframe crossmember: I really didn’t want to cut this. And then I cut it. I took a notch out of the rear of the crossmember, flipped it upside down, and re-welded it to allow more oil pan clearance. Not a big deal. The V6 puts more of the engine rearward of the crossmember and that, plus the oil pan sump design (mentioned below) necessitated the change.

Firewall:

Because the engine sits farther back than the 5.0L V8, I was getting some interference with the firewall just above the transmission tunnel and the intake manifold runner control (IMRC) solenoid on the rear of the 4.2’s lower intake manifold.

A five pound sledge hammer, a hunk of 2x4 to use as a drift, and some careful application of force resulted in enough clearance (only about a half inch) for the IMRC but with little evidence of brutality.

Transmission crossmember:

Pretty straightforward. I moved the crossmember to its rear-most position on the chassis. Cut the raised portion out of the middle of the crossmember, welded reinforcement in a lower-profile (flat) shape, attached a lower-profile mount (Crown Victoria), marked and drilled for the single stud on that mount, and that was about it.

Engine configuration:

Several modifications to the stock 4.2L were needed in order to make it fit comfortably. It does not enjoy the luxury of the Windsor V8’s “double hump” oil pan. The 4.2L has, unfortunately, the largest oil pan sump of all the Essex V6s which was not going to fit behind the crossmember without a lot of modifications. The ’04 Mustang pan was quite a bit better so that’s what I went with- it caused an issue with clearing the 4.2 stud girdle but with the Mustang stud girdle, all was well. I now have about two fingers’ width of clearance between the oil pan and notched cross member which seems pretty safe, even as the mounts age and compress.

Exhaust manifolds:

The 4.2L manifolds are problematic- the passenger side collector points 15 or 20 degrees away from the motor, meaning that it directly faces the sheetmetal above the lower control arm mount. The driver side almost fits but gets very close to the steering shaft. The less-than-ideal-but-acceptable solution is to use Thunderbird exhaust manifolds which tuck in close to the motor. These manifolds are obviously restrictive when compared to the van manifolds but they at least work. The hunt continues for Supercoupe manifolds or (even better) headers.

Intake manifolds:

The 4.2 has its idle air control motor parked sort-of obscenely on top of the upper intake manifold, adding at least an inch and a half to the overall height of the engine. This hit the bottom of the hood and it was evident that without major adjustment to engine height (which could have been accomplished but would open up various cans of various worms), something else would need to change.

The split port 3.8 / 3.9 / 4.2 all use functionally identical lower intakes, so the uppers exchange without issue. The split port Mustang upper intake is a far lower-profile design than the 4.2 and was a natural fit for the Volvo application. There is one negative side effect, however, and it is addressed in the next section.

Fuel:

The Ford 4.2 (at least, in the year of van from which my motor originates) uses a return-style fuel system and fuel pressure regulator mounted directly to the fuel rail. Fuel goes in at a constant 45+ PSI, and what’s bled off by the pressure regulator is sent back to the tank. On the other hand, the Mustang 3.8 / 3.9, starting in 1999, uses modulation of the fuel pump’s output to control fuel pressure at the injector rail (which is measured by a sensor on the rail) and as such, has no provision for a pressure regulator or return line. This would be inconsequential except that the tall 4.2 fuel rail would not fit beneath the low-pro Mustang upper intake. And of course the 4.2 ECM is not well set-up for making use of the Mustang’s more-modern fuel control system. Great.

The decision was made: use an external fuel pressure regulator. With this regulator I can connect the Volvo fuel supply line (that would otherwise connect straight to the stock redblock's fuel rail) and return line directly to the external regulator, and use AN-style fittings and hose to connect to the Mustang fuel rail. Other than cost and having One More Thing cluttering up the engine bay (and the not super-desirable side effect of fuel zipping around in an extra three feet of hose), the only other issue is that the damnable fuel rail pressure sensor is sticking out and interfering with the AC compressor feed and supply ports by about 5 mm; too much. See the AC section.

As for the fuel pump, I am reasonably confident that the Volvo pump configuration can keep up with the 4.2. If not, I have an Airtex inline pump to replace the Volvo pressure pump that will be more than peppy enough to handle the Ford all the way up to 300+ horsepower— a figure it will never see unless I get serious about forced induction.

Cooling system:

The Volvo has a decent amount of width available for a radiator and I really don’t think that the stock radiator (which takes up about 3/4 of the actual opening between the headlights) is going to be adequate for the Ford motor. One of the challenges of the Volvo is the relatively short height available in the front of the car. I measured, measured again, and re-measured everything and decided that a Volvo 850 radiator would fit. And fit it does. Perfectly. The core completely fills the grill opening and after making a couple of small lower rubber mounting pads from a truck mudflap, I was even able to use the factory 240 upper mounting brackets, placed in different (factory) holes on the core support.

Hoses have proven tricky but do-able. I’m using the Ford E-150 upper and lower hoses but heavily modified, with the Volvo expansion tank and a green cap. The upper hose has a billet adapter to downsize the hose for the radiator an in that adapter is a port for the “steam hose” that goes to the expansion tank. The lower hose on the E-150 has a built-in 1” port that goes to the expansion tank and serves as the fill point for the system. It’s worth noting that I had to cut all of these hoses and I’m not delighted by how they look. They seem functional but I wouldn’t be surprised if some re-work will be needed farther down the road.

For a fan, I’m using a mid-‘90s Taurus 2-speed fan (whose shroud matches the size of the radiator core quite well) and a Dakota Digital controller. If you have ever done this sort of thing you will understand, there is a dearth of options when it comes to good cooling fan controllers. The Dakota Digital unit can control a two speed fan (or two single speed fans), is configurable from an app, and looks to be generally far-better a device than most of its competition. I’m using the Ford sender output because I don’t have that wired to the gauge cluster (I have a separate VDO sender for the cluster in its own port in the supply hose to the heater core)

Power steering: Volvo hoses with a pressure-side adapter between Volvo hose and Ford pump. Don’t know if it will be over-boosted, under-boosted, or (and this seems highly unlikely), just right.

HVAC:

The plan here is to use some Volvo components in the Ford configuration and hope for the best. We’ve changed from the Volvo expansion valve system to the Ford pressure cycling system while keeping the Volvo evaporator core (a new one, albeit).

The condenser issue is a bit tricky. Since we’re using a a Volvo 850 radiator, my first instinct was to look at the 850’s condenser, as well, but the mounting for that is decidedly more complicated than the radiator and its hose configuration is proprietary in a way that doesn’t lend itself well to installation in a different vehicle. The best I’ve been able to do is compromise with a universal condenser (the compromise is that there’s nothing I can find that completely fills the front opening).

A Ford FS20 compressor from a 2007 F-150 gave us better placement of the inlet / outlet ports with only slight modification to the accessory bracketry. Custom hoses will of course be necessary.

Because the Ford motor sits so close to the firewall, there’s insufficient clearance between the driver’s side cylinder head and the Volvo heater hose ports for any sort of hose. I sealed up the firewall inlet / outlet passage on the driver side and with longer hoses on the inside, brought the heater inlet / outlet to the passenger side. I used generic stainless bulkhead through the firewall and the heater hoses now track down the passenger side strut tower and connect to the motor as they would from the factory.

Electrical:

My goal, from the get-go, was to have a car that, when you sat in the driver’s seat, would look and feel like A Nice Volvo. A well-cared-for European car with a modern accouterments. And that, to me, meant hiding (from the cabin, at least) any modifications to the Volvo infrastructure. After a lot (a lot: a measurement of time in days) of studying the Volvo and Ford wiring diagrams, I was able to begin the task of connecting Ford to Volvo.

Step one was stripping out the Volvo engine wiring. The Volvo Bosch LH-Jetronic is quite “modular”, meaning that it can be extricated from the car without leaving many cut wires. Like many Volvos of this vintage, the engine harness had begun to deteriorate significantly in places so it at least didn’t feel too bad puling it. Out came the factory ECM, ignition control unit, and most of the wiring under the passenger side dash.

It made the most sense to me to keep the Volvo philosophy whenever possible. So after removing the factory 20 amp ATC style fuse that fed the Bosch system, I added a 30 amp Maxi fuse and 10 gauge wire back into the cabin to feed the Ford system. I reused the Volvo-standard fuel and ECM relays and added one for the Ford A/C control. The Ford ECM controls the Volvo fuel pumps the same way it would control Ford fuel pumps. The Volvo momentary-on overdrive switch could connect directly to the Ford ECM for transmission control.

There were, of course, things that needed to be added. I used T5 bulb holders that have the same twist design as the Volvo instrument cluster warning lamps, but which draw their power from wires rather than contacts on the cluster PCB. One was used for the Check Engine Light (repurposed the Lambda Sond warning) and one was used for the OD indicator (repurposed [drumroll] the existing OD light for that).

Other minor changes were made for comfort: a rear-view mirror with backup camera display, a Viper security / keyless entry system (with added lock actuator for the driver’s door), seat heaters (with tasteful generic switches added to a painfully-good condition console), and LED lighting throughout.

All four of the headlight bulbs were in need of replacement so I took the opportunity to upgrade there, as well. I purchased a set of four glass housings that accept H4 bulbs and installed those in place of the sealed beam units. In the outer housings, I installed some middle-of-the-road (in price and reviews) LED bulbs. For the inner housings, I disconnected and tied up the Volvo high beam wiring, then installed yellow H4 headlight bulbs connected through a relay and two position switch (that will go where the factory rear foglight switch would go). The outer headlights are plenty bright enough as low and high beams, and with the two position switch I can run the inner “fog” lights either in low beam mode during regular driving without blinding oncoming traffic, or high beam mode when I’m in need of additional visibility.

The turn signal flasher had to be replaced with an electronic unit capable of handling the LEDs and it works well. I did run into a snag with LEDs and the Ford ECM. The Ford ECM monitors the brake light circuit and in doing so, puts a couple of volts onto the switched side of that circuit. Incandescent bulbs provide enough resistance to prevent them from illuminating but LEDs do not. The effect in this case was once you stepped on the brakes and put that circuit up to 12 volts then released the pedal, the lights would stay on dimly and the Ford ECM would read that the brake was still pressed. A resistor for just this purpose placed on the brake light wire was sufficient to solve this problem.

Another addition worth noting is the OBD-II connector that the Volvo, of course, did not have. These are readily available on Ebay and Amazon, so I bought one, wired it in to the driver’s side, and when I finally had the wiring sorted enough for power up, I found it pretty amusing to be communicating with my ’84 Volvo via my OBD-II scan tool.

The cluster illumination, center stack illumination, dome lights, and console light all got LEDs. The only interior lights that I did not change to LED were the seat belt warning bulbs which I think need to be incandescent for the timer circuit to work correctly.

The backup light circuit in the Volvo is activated by a switch either on the (manual) transmission or a switch on the (automatic) shift lever. Since I converted the car to an automatic and in the process, gutted the (non-functioning) backup light switch from the automatic shifter, I went ahead and connected the Volvo backup light circuit to the Ford-provided backup light switch that is on the transmission, itself. I believe that circuit typically has a relay on it, but the LED bulbs pull a small enough amount of power that I think it will be fine.

Instrumentation required some thought. As I said, I wanted the view from the driver’s seat to be very much Original Volvo. I found a new in box correct-looking VDO oil pressure gauge and hunted down a sender for it that has both analog pressure and warning light functionality, as well as threads that are correct for the Ford. The Ford ECM doesn’t care about oil pressure so that wiring can go straight to the Volvo cluster.

The Ford ECM does care about coolant temperature, and its scale is not the same as the Volvo sender so the Ford sender has to stay in place for that (and the cluster feed from the Ford harness was repurposed for the cooling fan controller). I bought a coupler that goes in the heater supply hose and has a threaded bung that accommodates the Volvo gauge sender. The oil pressure switch, coolant temperature gauge sender, and charge light are the only wires going back through the stock firewall plug and into the cabin.

Starter wiring, charge wiring, and main 12 volt supply to the Volvo fuse panel were massaged to integrate Ford and Volvo designs. The charge wiring is stock Ford save for the connection back to the Volvo gauge cluster. The starter feed (from the key) comes from the Ford engine harness and hits the Ford starter relay. In typical Ford design, the starter relay also serves as a 12 volt junction point where the battery cable meets the alternator feed, main vehicle power feed (Volvo fuse panel via the under hood junction block), and whatever other high-current circuits need power (in this case, that’s the cooling fan and 30 amp ECM maxi fuse).

At some point I will come back to this (hopefully) and update it with a more comprehensive wiring conversation.

Interior:

(Interior details here)

Install carpet, cleaned / painted interior trim
Rewire hatch / rear door
Paint, install front left fender
Install fuel pressure regulator and lines
Drain old fuel
Fab transmission cooler lines
Rebuild engine
Fab EGR pipe for Tbird manifold
Fab brackets for a couple of emissions-related items
Final paint, detail under hood
Exhaust system

Unnumbered Entry: The Volvo