oil pressure mystery

[kb123]

i have a 1600cc stock motor with solex carb and mexican block. is in our 66 ghia. only run it in the summer but put a couple thousand miles each year. external oil filter changed each year with oil.

started to get oil pressure light. mechanic says no oil pressure. checked the sump filter, blew through all the lines, replaced oil pump just in case. still no pressure. short of splitting the cases any ideas?

also best place to get rebuilt long block or complete motor?

any ideas are appreciated.

[Slow 1200]

have you measured pressure with a mechanical gauge or are you just relying on the idiot light?

[kb123]

mechanical gauge.

[Jim Ed]

also best place to get rebuilt long block or complete motor?

it's pricy but,
aircooled.net has one:

http://www.aircooled.net/new-bin/catsea ... E&perpage=
You might need a loading dock if it is a truck shipment.

I'd try every thing else before replacing the engine.
Maybe it just needs a new oil pressure sensor.

http://www.aircooled.net/new-bin/viewpr ... 1148226873

[doc]

Don't give up on your engine until you know what's wrong. It could be an easy and long term fix. How old is the engine? how many miles? Does it leak oil anywhere? Burn oil (have to add oil in less than 3000 miles)? Does the engine overheat? Does it have a lot of endplay?

Oil pressure problems come form 2 basic sources. Either the oil pump is not pumping or there is some blockage or leakage in the system. You've already replaced the oil pump, so chances are it's pumping. Now you're looking for a blockage (less likely) or leakage.

On a high mileage engine, everything internally may be so worn out that it just won't hold enough oil pressure. But lots of other things could be wrong that are much less disasterous. You need to find out what's wrong.

A little more info may help us assist you.

doc

[Weaponer]

When I replace an oil pump, I pack it with assembly lube to prime it. Did you prime your pump?

[bugman742002]

what weight oil are you using?

[Steve Arndt]

With the spark plugs removed, remove the oil pressure sending unit so the hole is open. Then crank until oil flows out the hole. Then fire it up with a gauge installed. This may help.

s

[kb123]

my old motor was a stock 1600 done on a mexican block. done 5 years ago. gets several thousand miles each year when weather is good. i am in nw montana. now no oil pressure. all external checks and new oil pump still no pressure. should i open it up? and what should i check/look for or consider a rebuilt long block or motor? am fine with stock as this is in a 66 ghia that is a summer car only.
your thoughts????????????
thanks in advance

[Stray Catalyst]

First, replace the oil pressure sender. You don't want to pull the motor to check something that you can easily and cheaply replace with the engine still installed. If you actually have no oil pressure and you've replaced the pump, there aren't all that may things left to check - the oil suction tube, perhaps?

Stray

[Marc]

First thing to rule out is overheating. Hot oil (or oil that's simply too low in viscosity for the conditions) is thinner and won't produce as much pressure since it escapes faster through all of the voids that it lubricates. ACVWs weren't designed for the ultralight oils specified for modern engines, so don't chase your tail looking for other problems if you've got oil lighter than, say, 30W or 10W-40 in there.
#1 cause of overheating is missing sheetmetal pieces or other openings that allow hot air from below the engine to recycle back up to the cooling fan inlet. Incorrect ignition timing can also cause overheating - use a strobe light to confirm that the advance mechanism is working correctly. Rule out a slipping belt or obstructed cooling fan. Grope the fan (with the engine off) for paper towels, tree leaves, small dead animals, etc.
It's rare for the pump itself to be the cause of low oil pressure, unless it's the wrong one for the application or extremely old. However, simply using the wrong gasket between the pump body and cover can cause a significant loss of pressure at warm-idle...it should be the tissue-thin one; if the thicker one intended for use between the pump and case is used for the cover there'll be too much gear end-play for good pressure at low speeds.
The oiling system in a VW incorporates one or two spring-loaded plungers which move in response to oil pressure in order to bypass the cooler when the engine hasn't warmed up yet, and to dump excessive pressure when/if it occurs in order to protect the cooler and seals from damage - although it's extremely rare, it's possible that a spring is broken or a plunger's stuck, so that needs to be ruled out. But DO NOT waste your time/money on any sort of "pressure booster kit" with stiffer springs or longer plungers, that is NOT the problem - healthy stock components are all that's needed.

Do you know the approximate vintage of your Mexican case? The numbers cast into the sides of the sump area should help to identify it. In later years, Mexican production engines went to hydraulic lifters and used bigger oil pumps with integral filters; earlier Mexican cases were nothing unusual. It's been too long for me to remember the details, but I recall there being an issue with certain Mexican cases regarding how a "normal" German or Brazilian oil pump's passages aligned with them...could be something going on there that's relevant to your situation.
One of the six studs that retain the oil strainer and sump plate is longer; it protrudes up inside the case so a tab coming off of the oil pump pickup pipe can be secured to it. If that stud's been replaced with a shorter one, or the nut inside came loose, or the tab itself broke, the pickup may swing up some which can allow it to suck air.

[jrandy]

I wonder if the ports in the oil pump match the ports in the case.

[kb123]

i will check all of this out. i love forums....
kb

[goober]

Does the pump plate have grooves? If so, find a smooth hard flat surface, a sheet of 400 grit wet/dry sandpaper, make 50/50 mix of hypoid oil/paint thinner and with circular motions remove the grooves from the plate. If you have access to a surface grinder, use it.

Install with as thin a pump/plate gasket as you can find, about .0045" thick.

[rte592]

Oil level check??
Fuel in the oil??
loose oil pick up tube??? (seen it before) sucks air and cavatates the pump
Can a stuck presure release valve stick in the open position???

Before you tear into it....
Remove the oil sender and fill the oil passage with oil (crank motor) see if the pump moves any oil.
If it does add a 1/2 qt and pump it out thru the sender hole into a container.

If it doesnt pump oil out
You should be able to pull the oil sender and pump (shoot oil thru the oil sender hole) (checking for a restriction)
From there remove the sump plate (shoot oil thru the other pump hole) to the sump (checking for a restriction)


Just noticed the date
Wed Sep 28, 2011
Wonder what he found?