Want to see the temp gauge on my van go up? Simple! Turn on the lights and heater blower.

I've already replaced the instrument cluster voltage regulator but that didn't do the trick. Now I'm thinking it's a weak ground.

Reading around on here I've seen it said that an engine block to firewall ground (or possibly even a ground to the steering column) might help my situation.

I've spent a fair amount of time underneath the vehicle, for one thing or another, but I can't recall ever seeing an engine block to chassis grounding strap.

QUESTION ----> does anybody know where I should be looking, or where a block to firewall ground strap should be, on my late '86 /early '87 carbureted 460 E350 cutaway camper van?

Thanks in advance for any advice that you may have.

 

Don't know about the cutaway's, but most V8 pickups had a ground from the rear bolt on the driver's side of the intake manifold to a spot on the firewall just behind and a bit right of that.

 

Thank you for the reply Gary, however with the van chassis the motor sits so far back that the firewall is about even with the 1st 3rd of the motor. The back of the motor sets way back inside the "dog house".

The van is set up with two batteries, the chassis battery and the house battery.

The house battery sits on the driver side and is grounded to the sheet metal next to the radiator. The hot lead runs to a solenoid that ties it in with the chassis battery when the key is on and there's another hot lead that runs back to the starter on the on-board generator.

The chassis battery sits on the passenger side and the hot lead runs to the starter relay. The chassis battery ground is sort of interesting in that half way to where it's bolted to the engine block the cable insulation is stripped away and there's a tang that's attached to the fender with a bolt...so the chassis ground is attached to both the passenger side fender and the block.

The fender attachment was hidden by the air intake duct work and it was a poor ground due to corrosion. I cleaned it all up thinking "Eureka! this has to be it!" only to be disappointed when I discovered that cleaning up this ground had no effect on my temp gauge.

Other than that the only other ground cable I found ran from the back of the transmission to the generator.

I looked all over the driver side firewall but didn't see any ground straps or cables, so at this point I'm thinking I'll scrape some paint to make a good connection and just attach a cable to the firewall and run the other end to the block somewhere.

Any other suggestions, advice, or encouragement would be greatly appreciated.

 

I didn't realize it is a van configuration, but that makes sense. As for the chassis ground, I'll bet that ground wire attaches to the frame not the fender. I just pulled mine off yesterday (Dad's Truck Build) and recognize the cable for sure. In my case the ground is about 9" to the passenger's side of the front of the engine, and the ground wire goes from the frame on to the corner of the engine, where it shares a stud with the bracket that routes the positive cable to the starter.

As for the "house" or vehicle ground, you need something from the frame or the engine (they should be the same, groundwise) as I'll bet your body is isolated from the frame and engine. So do what you are planning and scrape a place on the firewall and run a wire from the engine, like maybe the intake manifold, to the firewall. If your engine is grounded properly then you'll complete the circuit. Oh yes, the wire on mine is probably a #10 or larger for the engine to firewall ground since all the current for the accessories runs through it. Better to go larger rather than smaller.

 

the easiest thing to do is to just take a heavy wire and run it from the ground post of the battery to the sheet metal of the fender or whatever is convenient.

 

That works well - if the fender is electrically attached to the cab. Ford didn't do that for some reason.

 

Maybe because the hood is the ground plane for the radio? Keep it separate?

 

My hood had a ground wire to the firewall - I just took it off in the last couple of days so 'member it well.

As for Ford not using the fender for a ground, I was being ..... obtuse. Tongue-in-cheek. Fill in the blank. It depends on the electrical connection between said fender and firewall, both of which have just been painted when they assembled the vehicle.

 

If I remember, the wiper motor sits almost over the engine. I would just run a #10 wire from one of the wiper mount screws to a suitable point on the engine. If you use one of the replacement ground cables, they have a pigtail that GM products used for a body ground. 1992 and newer F-series use a similar system.

 

Thank you everyone for your replies, it is much appreciated.

First a few general observations:

I went to the junk yard on Tuesday to harvest the smog pumps off of a 1987 F250 pick up (a topic for another thread) and noticed on the donor vehicle both the hood to firewall ground strap and also a #10 gauge ground from the back of the intake manifold to one of the windshield washer motor mounting nuts on the firewall.

As for my E350 cutaway van there is no hood ground strap (and since I can't see any holes for one I don't think it ever had one) and the windshield washer motor is mounted inside the dash, back behind the instrument cluster and over to the left, I saw it back there when I had the cluster out to replace the IC voltage regulator.

Also, my E350 didn't have a block to firewall ground...until now.

I happened to have a chunk of #4 gauge that was the perfect length so I attached it to an open bolt hole on the front of the driver side head and then over to a 3/8" factory hole in the firewall, over by the kick panel just above where the firewall meets the curve of the wheel well. It turned out to be a neat and clean installation.

I've had the rig out for a couple long test drives and I'm pleased to report the temperature gauge seems to be behaving itself now. If I turn on the lights and heater blower it might go up slightly, only about the width of the gauge needle, but (so far at least) I'm really happy that it's not randomly pegging out or wandering up over the "L" in NORMAL.

However, the gauge still reads on the warm side. Reading 195 - 200F at the t-stat housing with an infrared thermometer, the gauge settles on the upper part of the "M" in NORMAL, but from what I can gather this is fairly typical for these old gauges.

So at this point I'm thinking the block to firewall ground has solved my wandering temp gauge problem but I do wonder if the #4 gauge might be too much and could somehow cause harm??? Please let me know if there's any reason for concern.

Also, Gary you mentioned on your F250 the battery ground went to the frame, and then to the block, but on mine, except for the tab screwed to the wheel well sheet metal, the negative battery cable is bolted directly to the block.

Would it also be advisable to add block to frame and body to frame grounds now, while I'm at it?

Thanks again everyone for your advice!

 

There is no such thing as too big of a wire in that situation. You are golden.

As for the battery ground, it would be good to add those grounds. Frequently lights are grounded to the frame, so if your frame doesn't have a good ground you should add it. Ditto the body, but you did that w/the firewall ground - right? Still, it cannot hurt and might help.

 

You will not completely eliminate the wandering gauges, there is a thread about this on here. The gauges used in these years are thermal and will change as the vehicle is driven.