96 850 Turbo Wagon Mechanic's Challenge

FlipIt · Post by **FlipIt** » 22 Jan 2011, 18:14

I've been looking thru the Volvo - Basic Diagnostic Procedures, 1995 ENGINE PERFORMANCE, 850 - Turbo. It looks like the fuel pressure with the fuel pump relay jumpered to run continuously and the engine not running should be 43.5 psi. If the pressure is low and I restrict the return flow the pressure should rise if the fuel pump is good. If I apply vacuum to the fuel pressure regulator with my hand vacuum pump the pressure should drop as the vacuum increases.

FlipIt · Post by **FlipIt** » 23 Jan 2011, 15:22

Today I let the fuel pump run for about twenty seconds and then cranked the engine. It fired and started to run and then stopped like it ran out of fuel. I removed the throttle linkage and connected my fuel pressure gauge to the Schrader valve. When I turned on the ignition the gauge jumped to 3 psi and then dropped back to zero even though the pump was still running. Using my vacuum hand pump I varied the vacuum to the fuel pressure regulator which made no difference. Then I cut the fuel return line hose near the fuel rail since I couldn't get it off and blocked it with a bolt. The pressure gauge still read 0 psi with the pump running. I have had problems in the past getting an accurate reading with a Schrader valve. I couldn't find my valve core remover so I will buy one tomorrow, remove the core and check the pressure again. Either the gauge reading was invalid, the fuel pump strainer is clogged, or the fuel pump is shot even though it runs.

FlipIt · Post by **FlipIt** » 24 Jan 2011, 18:11

I checked the fuel pressure at the rail with the valve core removed. It jumps to 3 psi at ignition turn on and then rapidly drops to 0 psi so I pulled the fuel pump.

: FPwScrn.jpg (38.28 KiB) Viewed 1874 times

The filter is torn and full of rust.

: FPBtm.jpg (54.12 KiB) Viewed 1874 times

The fuel hose has a split at the pump outlet and has the consistency of roofing tar if disturbed.

: FPPcs.jpg (62.24 KiB) Viewed 1874 times

For now I'll clean up the assembly, install a new filter, replace the fuel hose and reinstall the pump in the tank to see if I can get enough pressure to start the engine.

Post by **Ozark Lee** » 25 Jan 2011, 14:08

I haven't measured the supply voltage to the injectors yet. They could be clogged or not firing. I also could have a nonfunctional IAC valve. Tomorrow I'll try to start a few times while adjusting the throttle opening and measure the injector supply voltage.

You should be able to "feel" the injectors firing and normally they are louder than the lifters. There is synergy between the injectors and the IAC Valve, they both get their power from the master fuel system relay which is the gray relay mounted towards the driver's side of the fan shroud. The wiring to that relay is fairly exposed and I have seen the wires actually break.

The crud in your tank was actually much better than the similarly situated Porsche I had. It had an external fuel pump at the bottom of the tank and it wouldn't even turn on but here is what I had when I removed the fuel level sender.

: Fuel level sender - before.jpg (221.77 KiB) Viewed 1867 times

: Fuel pickup sediment bowl - before.JPG (217.5 KiB) Viewed 1867 times

Lacquer thinner works well when cleaning that stuff up.

...Lee

FlipIt · Post by **FlipIt** » 25 Jan 2011, 18:37

I haven't been able to find the correct fuel pump strainer locally. The parts stores listings show an Airtex FS205 for my vehicle but the opening for the pump is much smaller than the diameter required. After doing some research on the internet I believe that I have either an ARC or a Delphi fuel pump. I may have to order a Delphi strainer from Rock Auto which means a further delay.

FlipIt · Post by **FlipIt** » 27 Jan 2011, 18:36

I purchased some fuel hose, clamps and strainer (Airtex FS207) locally. I disassembled the fuel pump assembly, cleaned the electrical contacts and reassembled the pump with the new parts. With the return hose blocked I allowed the pressure to build up to 80 psi before switching off the ignition. The shop test procedure states not to let the pressure exceed 85 psi. Then I connected the unblocked return hose and tested the fuel pressure regulator with my hand vacuum pump. Everything was within specification so I installed the throttle body and linkage, the IAC valve and hooked up the intake hoses. I removed the fuel pump jumper and installed the relay and tested it for normal operation. When I cranked the starter the engine fired after a few seconds and then ran at idle speed. I shut off the engine after about 10 seconds since I had not replaced the coolant after draining the radiator.

Next I replaced the coolant reservoir which had a broken coolant level sensor, checked the hoses, and added my bottle of coolant flush. As I added the last of the flush I heard coolant leaking from somewhere and spashing on the garage floor. I know that I should have tested with water before using the coolant but I was anxious to run the engine long enough to let it warm up so I could test the compression. By the time I positioned a catch pan the leak had stopped. I lost about a third of the flush.

I hope that the coolant leak is not due to a cracked block, head or water pump. When I drained the radiator it contained antifreeze so the coolant should not have frozen at some time during the winters the vehicle was sitting. Maybe I'll get lucky and the block drain valve is not closed. Can someone tell me where the block drain is located?There is a maze of plumbing between the firewall and the engine that is very difficult to see and access. From just looking at it I can tell that it is not connected correctly. I have to research the cooling system configuration before proceeding with correcting the leak. Meanwhile, I'll complete the installation of the fuel pump which I just temporarily installed.

Post by **precopster** » 28 Jan 2011, 01:27

The block drain is beneath the exhaust manifold, about an inch from the water pump casting, and under the large coolant pipe. It is a 12mm head from memory.

FlipIt · Post by **FlipIt** » 28 Jan 2011, 14:05

precopster wrote:The block drain is beneath the exhaust manifold, about an inch from the water pump casting, and under the large coolant pipe. It is a 12mm head from memory.

Thanks to your help I found the block drain. Unfortunately, the leak was not coming from the drain. I removed the coolant reservoir to get a better look. Water leaks between the head/block and the timing cover as shown in the photo below.

: ClntLeak.jpg (61.44 KiB) Viewed 1745 times

VADIS has drawings of the rear of the engine and head but I haven't found a good one of the front. I suspect there may be a core (freeze) plug in the head that could be leaking. The water freely flows out when the water level reaches a certain height. The thermostat housing is higher than the leak but I didn't see water dripping from that area. I'll probably have to remove the serpentine belt and the timing belt in order to remove the timing cover to find the leak.

Post by **boosted5cyl** » 28 Jan 2011, 14:20

When I rebulit my T6 I had a leak that appeared in the same general area under the same circumstances. In my case it was leaking from the the turbo coolant pipe where it joins the head at the front of the motor on the exhaust side. My T5 has the same pipe in the same place.

If you look on the exhaust side of the motor you will see a coolant "rail" of sorts that goes the length of the motor. Where it was bolted to the head (left side if you are standing under the hood) I had a gasket issue. Pic attached with the leaking flange circled in red to give you an idea. Like I say, this pic is from my T6 but my T5 has the same pipe...

I tracked it down after pressurizing the cooling system. My symptoms were the same as yours. Leak in that area, looked to be behind the belt cover. It would fill to a point and then.......niagra falls!!!. Hopefully thats all it is. $2 gasket

Post by **precopster** » 28 Jan 2011, 21:03

The paper gasket is a PITA to replace, but you can flex the pipe a little with a crowbar to increase workspace.

There are a couple of expansion plugs there; the left one leads , I believe, to oil galleries as when I put my finger through the water coolant pipe hole I can't touch the back of the plug. The right one, however can be touched by putting my finger through the thermostat housing hole. This is the case with both my B5252S and B6304F spare heads in the workshop.
Part number is 946780.

I believe they are 29.5mm if the measurements of my B6304FS one's are accurate and share the same part numbers in Vadis as the B5234 .
I've attached a photo of the location below:

96 850 Turbo Wagon Mechanic's Challenge

Re: 96 850 Turbo Wagon Mechanic's Challenge