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  #1  
Old 12-14-2016, 12:13 AM
Retrohowla Retrohowla is offline
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Default New D24tic, what checks before tweaking?

Hi guys, just bought a 96 940 D24tic auto. She's on 140,000 miles (pretty low IMO) and sounds well.
I plan to tweak her up a bit for a more lively pull away and better driving experience but I'm not going crazy, but before I go tweaking anything I would like some advice on what to check/replace to ensure I'm at a good starting point.

So far the obvious being, full service, cam belts, water pump, check/set pump timing.
Who would recommend I replace the injector nozzles? Will they need doing at 140,000 miles?
Is there anything else I should be checking or renewing before improving performance?
As I say I'm not going silly, this is my daily and I want her reliable and bullet proof still.
I'd just like her to be a touch quicker off the mark and handle hills better, she's currently pretty limp!
Thanks in advance guys
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  #2  
Old 12-14-2016, 07:59 AM
v8volvo v8volvo is offline
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Congrats and welcome, sounds like a fun plan. These respond well to being turned up a bit, you'll be able to get it performing like you want without too much effort. The fact that you are starting with the IC motor gives you an advantage too.

I'd say you're on the right track with initial steps to get a good baseline setup. Timing belts, water pump, idler rollers/tensioner, set cam and pump timing to proper spec using the special tools. Make sure the bolt on the front of the crankshaft gets its correct torque using the special tools for that. Your late IC motor likely has hydraulic lifters but if not, check/adjust valve lash.

Replace fuel filter and air filter with good quality parts and ensure the airbox thermostat is working or stick it in the cold position, if your car has one. They can fail in the warm position and suck hot air all the time from the preheat hose which cuts down power. When replacing the fuel filter, prefill with clean new fuel or ATF, and make sure there are no old inner O-rings stuck on the filter nipple, sometimes they like to stay there and cause problems later on.

Replace the thermostat; I like to use the 80C version (may need to spec it for an Audi since sometimes does not show for the Volvo application) since it helps keep temps in check on long hills in hot weather, but if you never see high temperatures or do mountain driving the regular 87C tstat is OK. You'll be able to make whatever power you want with the engine, but the performance and integrity of the cooling system will determine whether you are able to reliably use it. Cooling systems are sensitive on these and the motor doesn't tolerate overheating, so give some attention to hoses, fan clutch, radiator, etc. Make sure it stays on proper temp at all times and if anything is marginal, replace before running it hard.

Check the cold start device for proper function; when they fail, they fail in the cold position and run the engine with too much timing advance when hot. As the engine warms up, you should be able to see the advance arm on the side of the pump back off fully to its stop, and if the idle and pump settings are set up correctly, you'll notice the idle speed drop from high idle to normal idle when warm. If it doesn't move, you can replace the wax thermostat that runs the system, or temporarily (or permanently) disable it in the warm position and live with rougher cold starts and no fast idle. Some folks don't mind this or live in warm places where it's less of an issue. I prefer to keep it working properly since it's a benefit in the cold months.

Pulling injectors and having them checked is never a "bad" idea; but you may find they don't need it. Still could be fine at that mileage and nozzles and injector work can be costly. If you're having them out, remember to replace the heatshields and overflow hoses, and it would be a chance to also check compression if you are curious. Replacing at least the two rear glow plugs is always a good idea if the injectors are out too, since they are a pain to reach at any other time. The front four are easy to get to. However, I would probably leave all of this for later and put priority on the other work you named first. You'll probably be able to get it running very well on the injectors that are in it now and look at them in the future if desired. At 140k I would not expect new nozzles to make a noticeable difference.

If you say it's especially slow off the line, that could be due to timing being off from a previous belt change. Decent chance that just doing the basic maintenance work above will give a significant increase in performance. Beyond that, turning up the fuel a bit will give more response, and especially since you have the TIC motor, you should be able to get good results from increasing turbo boost by a few psi in addition. There are diminishing returns on this with the stock turbo so want to avoid going too far but you can get some nice extra push with a mild increase and no sacrifice in reliability or bottom end.

Beyond the initial upkeep, always use good full synthetic oil and keep an eye on the cooling system and it will last you as long as you want, with good performance, excellent reliability, and low ownership cost. Lots of good knowledge on this board if you ever have questions. Enjoy and let us know how it goes!
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Last edited by v8volvo; 12-14-2016 at 09:14 AM.
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  #3  
Old 12-14-2016, 10:07 AM
Retrohowla Retrohowla is offline
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That brilliant thanks.
I've noticed an oil leak today at the front of the engine, I guess the previous owner stream cleaned the engine before I viewed it.
Is there a known leak point on these like a camshaft seal or crank seal?
I hope it's not the head gasket
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Old 12-14-2016, 10:25 AM
ngoma ngoma is offline
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Depends on exactly where you are seeing the leak originate. Clean it again, and do a good visual inspection. remember that the leaking oil will usually tend to travel downwards, and to the rear, being blown back by the fan. Other common sources could be (from front top to bottom): oil breather hose, valve cover gasket, head gasket, turbo, oil pump gasket, oil pan gasket.
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Old 12-14-2016, 03:31 PM
Retrohowla Retrohowla is offline
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The source seems to be under the cam belt cover somewhere. I'm reluctant to clean in there for fear of damaging the cam belt
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Old 12-15-2016, 09:10 AM
v8volvo v8volvo is offline
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First guess would be the valve cover gasket leaking from the front where it goes over the cam bearing cap. Sometimes can leak from the corners. and run down the front of the head behind the belt.

The cam and/or crank shaft seals could be the source of the leak but it's pretty rare, seems like they more or less only fail as a result of incorrect installation/damage, almost never while in normal operation. A blocked crankcase vent system could cause a failure but that is not an issue these engines tend to experience, the CCV system tends to be trouble-free.

Failed oil pump gasket is known to be possible, ngoma and I repaired one which was labor-intensive. Also an uncommon issue, though, and we believed that one probably also occurred due to a damaged gasket on that engine which had been taken apart before, rather than a "natural" age/usage failure. This one is a massive and continuous leak if it occurs since the oil is under pump pressure here, so if it were the issue, you would have seen it immediately.

Head gasket would be extremely unlikely as a source for an oil leak in this area since the only oil pressure feed for it is at the head bolt on left side between cyls 3 and 4. There are three oil drain passages on the right side but they're only under crankcase pressure (i.e. none, theoretically). Would have to be a radical gasket failure to leak from these.

When you say under the cam belt cover, do you mean you see it generally on the front of the engine or is it specifically coming out the bottom of the timing belt cover near the balancer? Is the balancer wet/slinging oil out?

If you take the timing belt cover off, is the belt wet?

Cam or crank seal failure will wet the backside of the cam or crank sprockets and then fling oil off radially. Big mess but it's easy to pinpoint if this is the issue.
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  #7  
Old 12-15-2016, 09:23 AM
Retrohowla Retrohowla is offline
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That's excellent advice thank you.
I would say from what you've described it's the cam cover that's at fault.
There is oil all around the back if the cover and the belt is wet.
I expect I will get a chance to investigate properly over the Christmas break, but for now I can live with it, it's not a massive leak.
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  #8  
Old 12-15-2016, 12:32 PM
ngoma ngoma is offline
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Oily belt will cause it to prematurely deteriorate and fail. You'll want to plan to replace it soon.

Valve cover gasket has a few failure modes:

1. There is a commonly available cork-sided version that is a proven leaker. Difficult to get this type to seal. The all-rubber version is better.
Solution: replace cork gasket with good quality rubber gasket.

2. Sometimes the shouldered studs get partially backed out during a VC gasket replacement. Subsequent tightening of the nuts bottoms them out on the (now raised) stud shoulders before sufficiently compressing the gasket.
Solution: Make sure the studs are bottomed in their holes before installing the VC/gasket.

3. Warped/bent VC or incorrect/uneven fastener torque. Too tight may distort the VC sealing surface.
Solution: Inspect VC sealing surface and repair if necessary. Torque down the nuts evenly, in steps, like when torquing down a cylinder head. One or two fingers on a 1/4" ratchet handle seems about right.
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  #9  
Old 12-15-2016, 12:42 PM
Retrohowla Retrohowla is offline
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Yes I'm planning to Change the belt and tensioners very soon. I'll inspect the valve cover gasket and see what I find. Thanks again for all the advice guys, really appreciate it.
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  #10  
Old 12-15-2016, 05:53 PM
S&W 629 S&W 629 is offline
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My car had a leak from the mating surface of the oil pump. Someone in the past had removed the oil pump and used a screw driver or other tool to pry off the pump and put a shallow gouge on the mating face of the pump. I removed the pump and had a bead of weld applied to the gouge and then had an automotive machine shop mill the surface perfectly flat again, then reinstalled the pump.
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