1983 D24T running warm

[VolvoGabe]

Originally Posted by v8volvo

If the temp gauge stopped working at the same time that you replaced the tstat, possible there is an air pocket in the system. Good idea to make sure all air is bled out since this will also cause overheat if the pocket is large. Another possibility is that the wire got pulled off the gauge sender (at front of cylinder head just ahead of #1 glow plug) if the wiring harness that runs near the tstat housing got moved during the work.

90 degree tstat would be a little warmer than stock, 87C is the OE temp. 3C might be enough to make a visible difference on the gauge, these are quite sensitive. If the car had no thermostat installed when you got it, that's a clue that the warm running you are noticing was going on for a previous owner too. The plugged radiator could have been a cause, good that you found that and fixed it.

I would start by checking the electrical connections to the temp gauge sender and making sure the cooling system is well burped, then see what happens. First of all you need the gauge to work. If all the wiring appears OK, you can test the circuit and the gauge by grounding the connector for the sender. The gauge should read full hot with this wire grounded. If it does but you still get no reading when it is connected to the sender, then the sender is the issue (rare). If you get no reading when the wire is grounded, then the issue is with the gauge/cluster (rare) or a wiring connection somewhere between the engine and the dash (common). If you get to this point with no clear answers, reply back here and we can give some tips on further steps.

One factor with your 1983 model is that your temperature gauge shows variations in temperature around the operating set point. 700 series Volvos from late 1984 onward introduced "damped" dummy-style temperature gauges where the needle stays right in the middle for any temperature relatively close to operating temp, roughly 180F-210F. With those later gauges, the only time you see it move up is after a problem is already happening, so the early warning an accurate gauge provides is lost. On your gauge you will see minor fluctuations that are normal. An extra few degrees of operating temp might be visible with a hot thermostat, which the later style gauge would hide.

A few of us have had success running slightly cooler thermostats for improving temperature control in hot weather. If other checks don't turn up obvious problems this could be something to try.

As others suggested - if the car sat 10 years be sure to replace the timing belt.

Also what are some signs the timing belt needs to be replaced. It starts turn of the key every time, and it does not smoke on idle and runs very smooth. Thanks

[VolvoGabe]

Sorry, I forgot to add the heater has been bypassed. Why? I don't know, was done by previous owner as it was a farm car and since he's 92 and in a rest home I didn't get to meet him as the car was sold on behalf.

[ngoma]

Originally Posted by VolvoGabe

Sorry, I forgot to add the heater has been bypassed. Why?

People often do this to temporarily "fix" a leaking heater core. What color and KPa marking does the coolant overflow bottle cap have?

[ngoma]

Originally Posted by VolvoGabe

Also what are some signs the timing belt needs to be replaced. It starts turn of the key every time, and it does not smoke on idle and runs very smooth. Thanks

Only sign is the engine will suddenly quit running. Upon further inspection you will find at least bent valves, damaged pistons, probably bent connecting rods as this is an interference engine. Therefore the 65,000 mile timing belt change spec. Note that if it has sat several years in the same position that can cause a "set" in the belt that may result in a premature (in miles, not chronological) failure. So if you don't know the history of the Timing belt, better change it. Requires special tools and knowledge, sorry no way around that. Lots of info on that in this forum if you look for it.

[VolvoGabe]

Originally Posted by ngoma

Only sign is the engine will suddenly quit running. Upon further inspection you will find at least bent valves, damaged pistons, probably bent connecting rods as this is an interference engine. Therefore the 65,000 mile timing belt change spec. Note that if it has sat several years in the same position that can cause a "set" in the belt that may result in a premature (in miles, not chronological) failure. So if you don't know the history of the Timing belt, better change it. Requires special tools and knowledge, sorry no way around that. Lots of info on that in this forum if you look for it.

The car got a full service before I picked it up at a local mechanic. After I got it home 1400k's later, I took it to my diesel mechanic. He said it was a very happy and healthy motor. The D24T currently in the car is not the original engine, it's still a 83' D24T motor but it has under 100,000 - he didn't specify k's or miles. I will replace anyway, better safe than sorry. Is it a timing belt or a timing chain? and where can I buy them? Thanks

[ngoma]

Originally Posted by VolvoGabe

He said it was a very happy and healthy motor.

That is great news! Easy starting, good power, low smoke, quiet smooth idle are all good signs.

The issue with an old timing belt is similar to old tires. The "rubber" compound degrades, cracks, and becomes less pliable. Chunks can separate, etc.

Originally Posted by VolvoGabe

Is it a timing belt or a timing chain? and where can I buy them? Thanks

Fiberglass-reinforced belt.

My FLAPS has them (Autozone, P/N 95083), yours might also. Time before that I got a Continental brand [CONTITECH TB083 {#069109119A, 1257223, 3507227} Length: 44.63 (in), 1134.00 (mm); Width: 1.00 (in), 25.00 (mm); Number of Teeth: 119] belt from Rockauto. Not expensive.

Might as well get a valve cover gasket because you will be opening that up. Not sure ATM where to get the one-piece all-rubber ones. If you are going to order from Rockauto, see if you can get them to describe the VC gasket style. Their pictures show the old 4-piece cork north/south + rubber east/west sections that were always leakers, but unless those are real old stock, I had heard that the only ones currently manufactured are the one-piece black "rubber" ones that seal better, so maybe that's what they actually send?

[VolvoGabe]

Do you think a block flush would help? Do the D24T's even like an acidic block flush? Just thinking that sitting for 10 years in a farm industrial area, it could help because all off the crap it collected over the years of sitting.

[ngoma]

What is the specific problem you are trying to solve with a "block flush?" What is a "block flush?"

[RedArrow]

I think he means getting rid of all leftover debris by flushing the engine (="block") completely, allowing higher pressures of water entering for a longer period of time then reversing the direction and keep switching between routes of "flushing" through the entire cooling system, including the engibe block itself.
The overheat problem probably runs somewhere else though. I suspect the wrong thermostat too. He has a lot of things to confirm before trusting it.

I heard citric acid works wonders but after ten years of car sitting untouched (AND unknown history of proper maintenance) I would definitely stop experimenting around the cooling system and probably would decide by a full (real full) tune-up... Valves adjusted --- at the minimum, then hoses, top gasket and all you can think of, including getting fresh nozzles, glowplugs, and maybe much more (check and flush and adjust pump, do waterpump, belts and possibly even check wiring).

I hope it turns out to be a great runner!!!
As #1, I dont get it why PO ran it without the thermostat.