Repairing the SCV Suction control valve

Petrol, gas, fuel tanks etc

Repairing the SCV Suction control valve

Postby Greytriton on Sun Sep 21, 2014 12:50 pm

Most of us have had a suction control valve replaced under warranty or had to buy a new one as its playing up, throwing codes, etc.

Ever wondered why it stuffs up? I have. I have had a few tritons over the years, suction control vales replaced under warrant multiple times and also bought replacment items to have them play up within 10-20,000km. Its annoying as hell.

Looking on the Internet you can buy standard replacment items or there is a 'heavy duty' modified SCV available. Reading the fine print in the advertisement it gives away the secret of what process has bee done to make this special item a 'heavy duty' special $100 more expensive part than standard.

It reads in the advertisement:
"Hi Spec Suction Control Valves will deliver more power over the standard unit by allowing the Common Rail Pump to make more available fuel for the ECU to control. Also, our Hi Spec Suction Control Valve is a more durable SCV over the standard version. It WILL LAST LONGER. Use this valve if you think the fuel available on the trip will be suspect!'

"THIS IS A GENUINE DENSO PART WITH A MODIFICATION."

What does this mean????

Well it gives it all away in the description above!
1. It is a standard genuine Denso part with a modification carried out.
2. It will last longer, use this part if you suspect your using suspect fuel.

So to analyse this you also need to look at the stripped failed item. On replacment the factory also replaces the fuel filters as part of the kit. This can only mean one thing. Standard SCV valves fail from contamination. The close tolerances in the SCV makes the small spool get jammed, scored and stick. The truck malfunction etc.

The answer is simple. The modification carried out on the standard modified so called 'heavy duty' SCV valve is clearancing.
The small spool is clearanced so that it can accomodate more not so good fuel, not get jammed and likely never to stuff up again. The trade off as also stated in the advertisement is slightly lumpy engine idol. Big whoop.

I've taken my stuffed 130000km SCV and carried out this special mod for free. No racing sticker on my stock SCV valve but same performance as the new one for $$$

1. Remove the Internal Circlip in the end of the valve.
2. Remove the small spool noting the direction it came out and also the spring. You can clearly see how the contamination in the fuel scores the spool and causes it to malfunction and jam
3. I put a bit of tape on a drill bit and mount the spool so you can spin it in a drill or similar.
4. Using some 2000grit wet or dry polish the score marks from the spool. I lubricated with some wd40 as I polished. So in this process we remove the score marks and also clearance the spool so it can't jam as easy. The amount of material removed is minimal with super fine 2000grit. Just a minute or two of polishing is required.
5. Clean all components very well with brake cleaner and re assemble.
6. Bobs your unkle. Fit racing heavy duty sticker.

Say all you want. I've got a new one on the shelf in my garage but it's not required. The clearanced polished item which is over 100000km old is just as good. Lumpy idol is barely noticeable if at all and is yet to miss a beat in over 20000km since I've carried out this mod.

Valve removed
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Circlip
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Score marks clearly visible on the SCV spool
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Mount the spool on a drill bit
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Last edited by Greytriton on Sun Sep 21, 2014 1:50 pm, edited 3 times in total.
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Sun Sep 21, 2014 12:53 pm

Scored spool close up
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Mounted in the drill press
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Polishing for a minute or two.
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Polished spool. All clean and clearanced
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Clean up all parts and re assemble.

Job done.
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Re: Repairing the SCV Suction control valve

Postby srb on Sun Sep 21, 2014 3:01 pm

:shock: Hmmm can't do that with mine as it's a sealed unit. :roll:
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Re: Repairing the SCV Suction control valve

Postby srb on Sun Sep 21, 2014 3:13 pm

The SCV you have is the same as the one that I first tried to fit. It won't fit my fuel pump. I've already tried. :cry:

Great idea for those that have this type of SCV. However I wonder if your're just prolonging the inevitable. Break down of the electrical coil. :-? Time will tell I guess. Good work!

This is the one like yours, has the circlip. ;-) Unfortunately it will not fit certain MN's or ML's
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Last edited by srb on Sun Sep 21, 2014 3:18 pm, edited 1 time in total.
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Sun Sep 21, 2014 3:18 pm

The fault with 99.9% of SCV failures won't be the coil. It is sticking spool from scoring. Then the ECU can't control it properly and it will throw a code.
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Re: Repairing the SCV Suction control valve

Postby srb on Sun Sep 21, 2014 3:37 pm

Greytriton wrote:The fault with 99.9% of SCV failures won't be the coil. It is sticking spool from scoring. Then the ECU can't control it properly and it will throw a code.


I agree mostly on what you say there but not so much with the 99.9% of them remark. Would probably more like 80% but hay lets not split hairs over it. ;-)

Yes dirty fuel plays havoc with these SCVs and the factory fuel filters are not enough to safe gaurd the CR system. Best to use secondary filtration as well.;-)

You also can't rule out the combination of the SCV coil getting weaker too. ;-)

I commend you for diving in and making us aware that some of these SCV can be serviced. ;-) Would be a great option for a lot of folks on here. 8-)

I wish mine was serviceable. :roll:
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Re: Repairing the SCV Suction control valve

Postby Cowboy Dave on Sun Sep 21, 2014 4:07 pm

So the pink one is the earlier model and the sealed one has the blue end on it? Bit of a trap that one as SRB and I found out.

You've got me awfully tempted to pull mine out as a maintenance item now even though it hasn't ever missed a beat.

I wonder if they might also be changing the spring in the upgraded ones?
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Sun Sep 21, 2014 4:34 pm

Why I mention this is that you can buy one that is a "modified Denso part" which apparantly makes it heavy duty. Buy a new one (like I have) and give it a bit of a polish which will give a bit more clearance and will not play up so soon like a stock one which has a very tight tolerance. Why pay $100+ for a modified standard part with a sticker on it.
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Re: Repairing the SCV Suction control valve

Postby Cowboy Dave on Sun Sep 21, 2014 4:38 pm

Yeah I'm not disagreeing with you on the fix. Just wondering out loud whether as well as polishing them up they might switch that spring out for something different since there's not that much else in the part. As we don't know anyone who has stripped the upgraded one we're only really guessing at what they've done to it.
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Sun Sep 21, 2014 5:44 pm

I've run one with a shortened spring by a few coils to reduce solenoid coil force required. Idol speed requires most current so a reduced current required to maintain control. Seems to work ok and didn't have any different feel at throttle application. A heavier spring would work adversly and would make the solenoid 'work harder' so that's why I tried a reduced spring. I'm talking like 3 or 4 coils.
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Re: Repairing the SCV Suction control valve

Postby coughy on Tue Sep 30, 2014 7:54 pm

So how is the tests going greytrition??
any more info that you would like to share?
how is it going with the mod?
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Re: Repairing the SCV Suction control valve

Postby ryan on Tue Sep 30, 2014 10:06 pm

I would like to know aswell, thinking about doing it to mine (if I can)
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Re: Repairing the SCV Suction control valve

Postby 4wd26 on Wed Oct 01, 2014 6:13 am

That is a great mod and thanks for taking the time to write on the forum about it
I'm sure that it will get a work out, I need to do myself
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Re: Repairing the SCV Suction control valve

Postby Dcpua2 on Sat Oct 04, 2014 7:05 pm

Tried this and now my car won't start, what did i possibly do wrong???
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Tue Oct 07, 2014 4:31 pm

I have had no issues. Both valves I have modified as per the above pictures are running perfect. Don't throw out your old ones. They just need a polish (unless the coil actually died - not likely).

Other than that a slightly lumpy idol. No dramas at all.
Last edited by Greytriton on Tue Oct 07, 2014 4:35 pm, edited 1 time in total.
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Re: Repairing the SCV Suction control valve

Postby Greytriton on Tue Oct 07, 2014 4:33 pm

Dcpua2 wrote:Tried this and now my car won't start, what did i possibly do wrong???


Spool installed backwards? Didn't plug it back in? Wash everything thourourly before re assembly? left the spring out? Does it move freely once assembled? Rubber orings damaged when re fitted?
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Re: Repairing the SCV Suction control valve

Postby Dcpua2 on Thu Oct 09, 2014 4:20 am

Click to view larger picture
This is how it looked when I removed it from the engine.
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Re: Repairing the SCV Suction control valve

Postby Dcpua2 on Thu Oct 09, 2014 4:22 am

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Re: Repairing the SCV Suction control valve

Postby ryan on Thu Oct 09, 2014 6:56 pm

Did doing this mod stop surging problems?
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Re: Repairing the SCV Suction control valve

Postby Steve1000 on Sat Oct 11, 2014 4:27 pm

:D Thanks for the tip mine started surging very slightly at about 2200rpm striped SCV down no excessive where to be seen used solvo autosol to polish up came up a treat and now runs great

Once again thanks
Last edited by Steve1000 on Sat Oct 11, 2014 9:00 pm, edited 1 time in total.
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Re: Repairing the SCV Suction control valve

Postby Octaneruss on Sat Oct 11, 2014 5:50 pm

Great post Greytriton! I think mine could be starting to play up a little so i will do the mod at 105000 KM service, I have run a Racor 2 micron filter from 50000KM when I bought the car and have always used EDT additive in BP fuel but have now switched to caltex as BP fuel is smokey with a chip and no CAT, again great info .
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Re: Repairing the SCV Suction control valve

Postby aimstix on Sat Oct 11, 2014 7:59 pm

Might sound like a stupid question but how do I find and remove my scv? My triton has been running rough sporadically and I have changed the fuel filter a few times thinking it would solve it.. and these sound exactly like my symptoms.
I'm very mechanical and have worked a lot on my cars just haven't looked for it yet lol
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Re: Repairing the SCV Suction control valve

Postby coughy on Sat Oct 11, 2014 8:50 pm

aimstix wrote:Might sound like a stupid question but how do I find and remove my scv? My triton has been running rough sporadically and I have changed the fuel filter a few times thinking it would solve it.. and these sound exactly like my symptoms.
I'm very mechanical and have worked a lot on my cars just haven't looked for it yet lol


look down behind the battery there is the scv bolted to the motor fuel pump towards the front of the engine.
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Re: Repairing the SCV Suction control valve

Postby Steve1000 on Sat Oct 11, 2014 9:16 pm

aimstix wrote:Might sound like a stupid question but how do I find and remove my scv? My triton has been running rough sporadically and I have changed the fuel filter a few times thinking it would solve it.. and these sound exactly like my symptoms.
I'm very mechanical and have worked a lot on my cars just haven't looked for it yet lol


Hi I have two tritons a 3.2 and a 2.5 the SCV on the 3.2 the is slightly difficult to get to it is on the passenger side of the engine about 250mm back from the front of the engine and about 250mm down from the top of the engine were as the one on the 2.5 ins on the same side a bit easier to get to about 150mm from the front and about 200mm from the top the SCV on my 2.5 is bigger than the one on the 3.2 hope this helps
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Re: Repairing the SCV Suction control valve

Postby aimstix on Mon Oct 13, 2014 7:33 am

Thanks guys.. had a look yesterday and assuming it's on the feed line to the pump... looks.like a shit to get to.. amy one have any tips like removing the battery ect.. might just book it in lol
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