Water Hose Diameter

[M36]

Just changed the water pump on my '97 Merc 200 efi. Always had low pressure at the gauge and found out it was plugged with something. After the new pump the water pressure was approx at 3 psi but when I changed the pee hose to I believe a 7/32 id hose, the pressure went up to just above 5 psi and the pee tube is shooting across the yard.

What is the correct diameter water hose for this if what I have now is wrong? I have seen it should be below 5 at idle.

Found this from EuropeanAM :

"If the engine actually is a 200 EFI (built in 2001 production year range), the water pressure specs are:

IDLE: 2-4 psi MINIMUM
WOT: 12 psi BARE MINIMUM (prefer to see 15+ psi for safe measure in turns)."

[fly by night]

Our gurus are all busy assisting other customers but will be back shortly.

[EuropeanAM]

If you installed a complete water pump kit.... Pressure may be elevated for a couple trips to the water, and then settle down.

Telltale hose should have been coming from the thermostats, there should be little (or no) telltale until or unless the thermostats are open. Normally this tubing is 5/16" ID, and it connects to a telltale fitting that exists the cowling (which has an opening ROUGHLY 7/32". Are you missing the cowling fitting and using a hose instead?

[M36]

Hi European, thanks for chiming in. I'll describe as best I can. The telltale hose comes from the fitting on top between the heads. there is a T in the line near the fitting that goes to the water pressure gauge, then it continues down through the hole in the bottom and out. Nothing until it warms up which starts within 10=12 seconds I believe. Don't know if it makes a difference but this time I ordered a Quicksilver kit instead of the SEI Marine kit I got two years ago. Yes the fitting is gone and just run the hose out the hole. Honestly I wasn't aware there was a fitting for that. It's just been the hose ever since I have had it.

[JOE54]

needs the fitting for restriction

[EuropeanAM]

And the telltale comes from the thermostat circuit (NOT from the fitting atop the engine).

[M36]

Been out of town and couldn't post this. Is this called the thermostat circuit and the hose from the circuit to the T to the telltale should be 5/16 id? The T part goes to the pressure gauge and is less than 5/16 and may be 7/32. I have the telltale fitting, just need to get the hose done.

IMG_8597.JPG

[EuropeanAM]

That fitting/hose was never supposed to go to the telltale. Telltale came from a different tee that should be in the thermostat circuit (running from one thermostat to another, to the adapter plate as a "dump" port, and to the telltale).

[M36]

What would you suggest? I've been running it like this for years but if it's not right...........

[EuropeanAM]

Can you snap a picture of the hose routings from the thermostat covers, and post?

[M36]

I hope this makes sense. The black hose bridges both thermostats with the clear hose spliced in on the port side , and that goes down to another black hose bridging two outlets on the bottom of the block. Then the telltale hose is as in the picture before coming off the top of the motor.

Attachment 544435Attachment 544436
Attachment 544437I also found a prior post for 1999 2.5 200 EFI hose routing. I think I have this figured out just need the hose sizes to get the right fittings. I think I have it.

[EuropeanAM]

Images did not upload- use the "picture frame" button in the Quick Reply window to upload your images one at a time.

[M36]

thumbnail_IMG_8617.jpgthumbnail_IMG_8618.jpgthumbnail_IMG_8619.jpg

Went to the lake today, at idle water pressure was right around 5 psi, and while running across the lake under throttle, same psi.

[EuropeanAM]

Very hard to discern the actual connections on the thermostat hose going DOWN (port side). The dump hose normally has a tee that feeds the TELLTALE.

The hose coming from the top of the block would normally go to the poppet bypass circuit (which permits air to bleed from the top of the block eliminating a steam pocket). This pathway may be restricted to adjust water pressure at idle, if required.

While I do believe your water pressure is affected by the unusual routing, specs are PURPOSELY provided only for IDLE and for WIDE OPEN THROTTLE.

Anything "in between" idle and WOT is just that: Some figure "in between".

[M36]

Hopefully these are better. The one hose goes from thermostat to thermostat with the clear hose going down to the black hose that is connected to the poppet and a water fitting on the port side. The telltale comes of the fitting behind the flywheel and T's off to the water pressure gauge. I saw in the other thread for hose connections that the down hose from the thermostat line show go to a T that then goes to the telltale. The zip tied smaller hose goes through the telltale hole from the top.
A hose on the top should go to the poppet through a 1/2" fitting. Think that was right. thumbnail_IMG_8665.jpgthumbnail_IMG_8666.jpg

I have been working on this this morning going off some other threads. When I blow on the hose going into the poppet valve, air goes right through. I read there should be no air at all and if that is the case, the damn HACK that built this may have left it out. Maybe this is the reason the water hoses are routed the way they are.

[EuropeanAM]

The hose running to the poppet (from the top of the block) can indeed flow toward the poppet under all normal engine operating circumstances. This circuit permits AIR POCKETS to pass/bleed, ensuring the entire block fills with coolant.