obd1 vr6 top end rebuild problems, tappets? timing? any help apreciated

[duncgti 10]

Hi. Bit of a long story but hopefully someone here will have some good advice. my 1994 vr6 has been of the road going on a year whilst i sorted out body work and gave it a general overhaul. The last thing on the list to do was strip the head off and replace the valve steam seals as 2 of the plugs were getting oil on them and causing a misfire. So me and a friend with a good mechanical back ground striped the head off the car removed and numbered all tappets and there relevant positions, no signs of bore wear in the bottom end, but the valve stems were rather coked up. cleaned everything down so it was spotless changed out the valve steam seals and removed all carbon deposits from the valves and re lapped them in spending a good few hours getting it done right. We then put the head back on with new gaskets all round, new crack pipe, thermostat housing, oil filter, basically any parts that looked even slightly dated got changed for new. Re mounted the cams and tappets (these had been cleaned of old oil) and set the timing using a cam lock plate and re attached the cam gear. Turned the engine by hand whilst checking the timing mark and all seemed good, put in new coolant and oil then set about firing her up.

After spinning the engine with no plugs to build oil pressure we put new plugs and leads back on and fired her up. Started first turn of the key but still had a slight misfire and a more pronounced tappet noise which we thought would go away after oil had re circulated around the head. the noise is still there after 20 mins of leaving the car running, and bringing the revs up to 3000rpm sounds even worse! the tappets were the only thing that i didn't change along with the timing chain guides as they were in great condition.

Does anyone have any ideas on what the problem could be and what i could try to fix it or if i have missed something silly? we triple checked the timing so i cant see this being an issue but just don't know where to go. It ticks over but when you put your foot on the throttle quickly it bogs down before the revs climb.

A mechanic has told me to sit the car at 2-3k rpm to build pressure up in the tappets, is this OK to do? or is my best option take it back apart and put in new tappets? i really want to get it back on the road after putting so much work into it. i feel the misfire may be due to a sensor so will get it on vag com asap but really need to sort this tappet issue.

 

sorry for the essay i thought the best was to get a good answer would be to give all the details on whats been done. any help would be much appreciated.

[lilfuzzer 1]

Was the tappets noisy before the rebuild?

[duncgti 10]

ever so slightly but nothing like they are now, also the car runs very clean no smoke at all.

[lilfuzzer 1]

maybe the tappets are stuck?

[lilfuzzer 1]

Maybe the old oil has clogged up the tappets and not letting them move

[duncgti 10]

that could be the case, is there any way to free the tappets up without stripping it back down?

[Dox 23]

Can you see oil getting to the cams?

 

I'd do an oil pressure test before you tear it down again

[duncgti 10]

no i haven't had the rocker cover off yet to check the cams that's on the list this weekend. The oil pressure light hasn't come but i haven't done an actual test.

[lilfuzzer 1]

I am no expert but think you would to strip back down. Hopefully someone more intelligent than me will advise otherwise. As Dox says if you have access to a test kit may save stripping down

[jamiehamy 0]

Is it actually misfiring? The reason I ask is that when I did my chains, on start up, it ran like a bag of spanners and we quickly identified running on 4 cylinders. My heart sank at the prospect of tking it all apart, but we were puzzled by the misfire - it didn't seem mechanical.

 

Switched off, unplug the battery, waited a few mins, reconnected, fire up - ran like a dream. Might not help in your cae, but you nver know.

 

Also, would it be worth running it through with engine flush and changing the oil? or even fling a dose of power stering fluid in and running it for half an hour or so before changing the oil.

 

Changing the tappets shouldn't take too long mind you, and make sure they have enough oil in the bores as they are meant to spin round as they operate (so I understand).

[Dox 23]

[duncgti 10]

it sure sounds like a misfire, i could run engine flush then replace the oil but i don't really want to put any additives in with the oil as its fresh castrol. I will try the battery trick on the off chance it works i mean the car hasn't had a good drive in over a year i think the ecu could do with being re learned, but again i would like it running well before i even attempt to drive it anywhere. also forgot to say when i put it back together fresh oil was pored over each tappet and the cam lobes so it was by no means dry when i first fired it. its also ticking over at a steady 750-800 rpm and not fluctuating which is a good sign as well i am just worried about this noise. would an engine flush loosen stuck tappets off?

[duncgti 10]

don't work dox the firing order is correct and its a dizzy cap model not a coil pack if that's any help to anyone.

[Jim Bowen 1]

Revving the engine to quieten the tappets is true. It tells you to do it when fitting new ones. Which you can get INA tappets on ebay for £80.

[duncgti 10]

i shall give that a try first then if not it may be best to change them out, they looked in good condition though. Thanks for the fast replys guys really appreciate it. I'll try and get a video up as well so you can have a better idea of the problem.

[Jim Bowen 1]

Also worth checking manifolds. Inlet and exhaust. just check the bolts are all tight.

[Dox 23]

don't work dox the firing order is correct and its a dizzy cap model not a coil pack if that's any help to anyone.

 

With the dizzy being on the passenger side of the engine the leads go in an anticlockwise direction, is that the way you've set it up?

[fla 9]

Dunc is there a lot of engine shake? What do the plugs look like? Have you tried pulling each lead to check for a spark? If everything checks out it may then be worth taking it for a drive and once up to temp to give it a good thrash to clean things out.

engine flush is really just a thin grade of oil which needs minimal time to get to operating conditions, although may have some snake oil additives!

[Wullie 1]

Also worth checking manifolds. Inlet and exhaust. just check the bolts are all tight.

 

I second this as a first step, simple and inexpensive. Had a similar thing with my 16v. After 5 minutes of panic thinking I'd left a socket set in the cylinders discovered the exhaust had a couple of loose bolts. Doh.

[duncgti 10]

ok i think my plan of action for the weekend is as follows

 

1 check manifolds make sure everything is nice and tight

2 triple check the leads!bit disappointed my new leads didn't come with a new king lead! and check for spark. check rotor arm matches its relevant position at tdc

3 pop the spark plugs out and check the condition (they are brand new ngk plugs so hopefully clean)

4 clean the isv valve (again this was replaced with a good condition one not long ago)

5 check for any air leaks just in case

 

i can't take the car for a test drive as it is sorn atm i am trying to get it all back together running nice for the mot. And yeah there is a bit of engine shake when the revs climb near 3000rpm could the oil pressure regulator have anything to do with the car running rough? i remember reading that somewhere? anything else i should look out for and check? any sensors that may have failed causing poor throttle response?

I went out to the car tonight to quickly try the leaving it running at 2500rpm for 10 mins trick to see if it helped and the car started having an erratic idle and a couple of loud back pops almost stalling,it was low on fuel but not empty which may have been the reason. which brings me to my next question i put 2 Jerry tanks of fuel in it roughly £10 worth and the car has used all of this, and has only been run up to temp a couple of times maybe half hour 45 mins running max so we can add excessive fuel consumption to the list as well! so fuel pressure regulator? fuel pump? all the injectors were flow checked and reconditioned less than 2000 miles ago so i know they are good.Going to leave it for Saturday so i can have a full day problem solving and ticking things off that are actually ok.

Anything else you guys can recommend to check? could the problems be caused by faulty ecu relay or anything else that isn't a common problem?

 

and again thanks for the help there are just so many causes for the problems its hard to pin them down.

[jamiehamy 0]

Popping, banging and using fuel? Defo check for airleaks, or a pipe off somewhere...first :) Usual suspects are the vacuum pipe on the rhs of the inlet manifold at the front, the pcv piping on the left running into the air intake and the one going into the fuel pressure valve again at the front rhs...talking from experience here! :(

Edited February 5, 2015 by jamiehamy

[duncgti 10]

nice one i shall check them as well all the intake rubbers are in great condition and the intake pipe has been changed for 42 draft intake like this

 

http://www.42draftdesigns.com/Mk3-VR6-Upper-Intake-Tube_p_339.html

 

as it had air leak problems when i got it, so i made sure it was sorted but i will double check all intake hoses just to be safe

[duncgti 10]

Bit of an update from today. Went out to the car and double checked ignition lead orientation which was all correct. Then went on the hunt for air leaks, i basically just double checked every join or jubilee was sitting level and tight and that none of the hoses were cracked or perished, again everything here seemed fine. I removed the rocker cover breather hose whilst checking for leaks and found a small amount of moisture/mayo inside,this got me a bit worried so took off the oil cap to have a look, all clean also checked the coolant levels which were good and no discoloration either. I checked online and apparently this could be due to moisture in the engine due to it sitting for a while. I don't believe the head gasket has gone as there is no smoke and its not using water. Also got a video so you guys can get a better idea of whats going on.

 

link

 

excuse the look of the car its still being worked on and needs a good clean and the last of the trim put on.

 

if anyone could have a watch and advise that would be great. I'm thinking isv valve it didn't do a thing when i unplugged it. Really need to get it on vag com to see if its throwing any codes. Next step is to check plugs and make sure all leads are firing probably going to change the dizzy cap and rotor arm just to be safe.

[duncgti 10]

Also at 48 seconds you can hear the revs just drop and the idle splutter and 2.51 how lumpy it is after throttle

[fla 9]

Mines a bit lumpy like that at present it certainly sounds like a sticky tappet. Mayo will be just as you said, because of standing for a while. Maybe worth driving around for a while to get the temp up. I've cleaned my (new) plugs a few times due to carbon and not getting the car up to temp (also sorn'd).