Glow Plug Light Stays On

[adamdrives]

Hey guys, the glow plug indicator light on my 85 d24t does not turn off with key in position two, even after the car is warm and has been driven. It has a new coolant temp sensor at the back of the head, which I may try swapping out with another new unit just in case. All the wiring is new and correct. The greenbook doesn't seem to offer any insight into this issue. Should I be concerned? The light shuts off once the car is started. The car came (non-running) with all glow plugs dead, and I'd rather not EVER have to replace #6 again.

The coolant temp gauge doesn't work, but that runs off of a different sensor, so I don't think it should make a difference.

Adam

[v8volvo]

You have a couple of important issues to address here.

First, forget about the glow plugs, and everything else on the car, until after you get the temperature gauge fixed or install some kind of alternative. Don't drive it without a gauge, you need to know the temperature and be able to react if it goes outside normal range. This engine is sensitive to overheating, if you have no way of knowing about it until you notice operating symptoms, then you're guaranteeing that even a very small cooling system problem will cascade to a complete engine failure. You'd hate to lose the car that way and it is avoidable. Fix this first, before you drive it another mile.

Then, to address the glow plugs, we need to know a little more about what you're working on. 240 or 740, and what year? 240s up through the first half of model year 1984 used a glow control system with two relays then from 1984.5 they used a single relay system. 740/760 has the single relay system for all years. It sounds as if you may have a relay issue, or a wiring problem that has not been found yet. The temp sensor in the head rarely fails. Does the light *never* turn off with key in II, or does it just take a long long time? Do the glow plugs remain energized the entire time?

If the car came to you with all 6 plugs dead, that's a good sign that there is a glow system problem. So yes, you should be concerned -- that will happen again if it remains this way and you'll have to get acquainted with that #6 plug again.

After you fix the temperature gauge, provide some more info on the car and the glow issue and we'll get it figured out. The system is simple and should be able to get put right without too much trouble.

[jpliddy]

hi volvo 8 my temperature gauge is broke too what do you recommend as a alternative temperature gauge that would look ok on a 940 diesel ?

[adamdrives]

Sorry, it's an 85 740 d24t. Thought I added that.

I grounded the coolant temp wire and gauge went to full hot, so it's the sensor. Have one on the way.

It must be the relay, the glow plug light comes on in pos. 2 but would previously never go out. Today the light wouldn't go off once the car had started, so I tried tapping on the relay and it went out. Then, with the car warm I started again and the light didn't come on, so it must have been working properly (seeing warm temp from sensor and not activating plugs). Either way, I'll be looking for a replacement relay. Don't suppose these are still available new from Volvo?

[ngoma]

Originally Posted by adamdrives

Don't suppose these are still available new from Volvo?

There is a newer version with better logic. Site search is your friend

http://d24t.com/showthread.php?t=156...low+plug+relay

[adamdrives]

Thanks, although I'm not sure that's the one I'm looking for. Link says looking for relay pn 899117, afaik I'm looking for 899104, although that doesn't come up in volvo catalog. Volvo pn on mine is 1348 339, $188 from tasca. Is the -117 a known good update for the single relay (post 84.5) cars?

[adamdrives]

Voluparts has a new relay PN 9162987 for $200 + ship, though that doesn't appear in any of the online catalogs I've checked. Tasca has a 1348339 (which according to Voluparts is a superseded PN) for $188. Can anyone confirm PN for newer version relay? Or have a good one for sale used? I want to have a backup for mine, which sometimes needs a tap to turn off.

[v8volvo]

Originally Posted by adamdrives

Is the -117 a known good update for the single relay (post 84.5) cars?

Yes, the -117 part number replaces -104 and has an updated design that gets rid of some questionable calibration in the 899104 relay that can occasionally cause long crank times for warm starting. The 899117 marked relay is the one you want. It may also have superseded to another one by now, and these markings might not reflect the correct Volvo part number which is usually 7 digits. One of the Volvo numbers you quoted may be the right one. The 89- numbers are probably the numbers of whoever supplies the relay.

I suggest calling your local Volvo dealer and asking them to look up a current part number for you -- they should be able to tell you whatever is the latest and greatest, confirm the numbers you have, and check availability as well. If they say they can get them, then buying one from Tasca will probably be the cheapest way to order one.

If they have difficulty getting them or the price is too steep, you can also use an aftermarket relay made by Huco that is a good quality part and also addresses the warm start issue. They way it does it is by lighting the glow plugs for every start, even a full hot start, rather than just increasing the warm-restart threshold temperature to trigger them as the updated OE relay does while leaving them off for full hot restarts. Arguably the increased usage might marginally decrease plug life, though even that is probably unlikely. The relay is physically a little larger and a tight fit on 1984+ 700 series cars that have additional components mounted adjacent to the relay on that same bracket on the strut tower, but it works. Here is a possible source to get one of those, I haven't bought one in a few years so availability could have changed but they still indicate that they may be able to get them: http://www.autohausaz.com/search/pro...lay/Controller

[adamdrives]

Thanks, I had seen that relay but wasn't sure if it was any good. My relay has an issue with the cut out circuit, the relay will click and the light will go out if I tap it during a warm restart, otherwise it will stay on as if I am starting cold. I am having warm start issues, so maybe it's related. Since the light was coming on I had started to think about a possible air leak.

FWIW that PN relay is available on the Skandix website for $120 shipped, though it doesn't appear genuine.

[adamdrives]

Success! Found a used -2987 newer logic glow plug relay used from Germany for about 100 usd shipped. Not new, but only price for new was 200 +ship.